Calculus Examples

$lim_{θ \to \frac{π}{2}} \frac{\sin^{2} (2 θ)}{1 - \sin^{2} (θ)}$

Step 1

Apply L'Hospital's rule.

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Step 1.1

Evaluate the limit of the numerator and the limit of the denominator.

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Step 1.1.1

Take the limit of the numerator and the limit of the denominator.

$\frac{lim_{θ \to \frac{π}{2}} \sin^{2} (2 θ)}{lim_{θ \to \frac{π}{2}} 1 - \sin^{2} (θ)}$

Step 1.1.2

Evaluate the limit of the numerator.

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Step 1.1.2.1

Evaluate the limit.

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Step 1.1.2.1.1

Move the exponent $2$ from $\sin^{2} (2 θ)$ outside the limit using the Limits Power Rule.

$\frac{{(lim_{θ \to \frac{π}{2}} \sin (2 θ))}^{2}}{lim_{θ \to \frac{π}{2}} 1 - \sin^{2} (θ)}$

Step 1.1.2.1.2

Move the limit inside the trig function because sine is continuous.

$\frac{\sin^{2} (lim_{θ \to \frac{π}{2}} 2 θ)}{lim_{θ \to \frac{π}{2}} 1 - \sin^{2} (θ)}$

Step 1.1.2.1.3

Move the term $2$ outside of the limit because it is constant with respect to $θ$ .

$\frac{\sin^{2} (2 lim_{θ \to \frac{π}{2}} θ)}{lim_{θ \to \frac{π}{2}} 1 - \sin^{2} (θ)}$

Step 1.1.2.2

Evaluate the limit of $θ$ by plugging in $\frac{π}{2}$ for $θ$ .

$\frac{\sin^{2} (2 \frac{π}{2})}{lim_{θ \to \frac{π}{2}} 1 - \sin^{2} (θ)}$

Step 1.1.2.3

Simplify the answer.

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Step 1.1.2.3.1

Cancel the common factor of $2$ .

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Step 1.1.2.3.1.1

Cancel the common factor.

$\frac{\sin^{2} (2 \frac{π}{2})}{lim_{θ \to \frac{π}{2}} 1 - \sin^{2} (θ)}$

Step 1.1.2.3.1.2

Rewrite the expression.

$\frac{\sin^{2} (π)}{lim_{θ \to \frac{π}{2}} 1 - \sin^{2} (θ)}$

Step 1.1.2.3.2

Apply the reference angle by finding the angle with equivalent trig values in the first quadrant.

$\frac{\sin^{2} (0)}{lim_{θ \to \frac{π}{2}} 1 - \sin^{2} (θ)}$

Step 1.1.2.3.3

The exact value of $\sin (0)$ is $0$ .

$\frac{0^{2}}{lim_{θ \to \frac{π}{2}} 1 - \sin^{2} (θ)}$

Step 1.1.2.3.4

Raising $0$ to any positive power yields $0$ .

$\frac{0}{lim_{θ \to \frac{π}{2}} 1 - \sin^{2} (θ)}$

Step 1.1.3

Evaluate the limit of the denominator.

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Step 1.1.3.1

Evaluate the limit.

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Step 1.1.3.1.1

Split the limit using the Sum of Limits Rule on the limit as $θ$ approaches $\frac{π}{2}$ .

$\frac{0}{lim_{θ \to \frac{π}{2}} 1 - lim_{θ \to \frac{π}{2}} \sin^{2} (θ)}$

Step 1.1.3.1.2

Evaluate the limit of $1$ which is constant as $θ$ approaches $\frac{π}{2}$ .

$\frac{0}{1 - lim_{θ \to \frac{π}{2}} \sin^{2} (θ)}$

Step 1.1.3.1.3

Move the exponent $2$ from $\sin^{2} (θ)$ outside the limit using the Limits Power Rule.

$\frac{0}{1 - {(lim_{θ \to \frac{π}{2}} \sin (θ))}^{2}}$

Step 1.1.3.1.4

Move the limit inside the trig function because sine is continuous.

$\frac{0}{1 - \sin^{2} (lim_{θ \to \frac{π}{2}} θ)}$

Step 1.1.3.2

Evaluate the limit of $θ$ by plugging in $\frac{π}{2}$ for $θ$ .

$\frac{0}{1 - \sin^{2} (\frac{π}{2})}$

Step 1.1.3.3

Simplify the answer.

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Step 1.1.3.3.1

Apply pythagorean identity.

$\frac{0}{\cos^{2} (\frac{π}{2})}$

Step 1.1.3.3.2

The exact value of $\cos (\frac{π}{2})$ is $0$ .

$\frac{0}{0^{2}}$

Step 1.1.3.3.3

Raising $0$ to any positive power yields $0$ .

$\frac{0}{0}$

Step 1.1.3.3.4

The expression contains a division by $0$ . The expression is undefined.

Undefined

$\frac{0}{0}$

Step 1.1.3.4

The expression contains a division by $0$ . The expression is undefined.

Undefined

$\frac{0}{0}$

Step 1.1.4

The expression contains a division by $0$ . The expression is undefined.

Undefined

$\frac{0}{0}$

Step 1.2

Since $\frac{0}{0}$ is of indeterminate form, apply L'Hospital's Rule. L'Hospital's Rule states that the limit of a quotient of functions is equal to the limit of the quotient of their derivatives.

$lim_{θ \to \frac{π}{2}} \frac{\sin^{2} (2 θ)}{1 - \sin^{2} (θ)} = lim_{θ \to \frac{π}{2}} \frac{\frac{d}{d θ} [\sin^{2} (2 θ)]}{\frac{d}{d θ} [1 - \sin^{2} (θ)]}$

Step 1.3

Find the derivative of the numerator and denominator.

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Step 1.3.1

Differentiate the numerator and denominator.

$lim_{θ \to \frac{π}{2}} \frac{\frac{d}{d θ} [\sin^{2} (2 θ)]}{\frac{d}{d θ} [1 - \sin^{2} (θ)]}$

Step 1.3.2

Differentiate using the chain rule, which states that $\frac{d}{d θ} [f (g (θ))]$ is $f' (g (θ)) g' (θ)$ where $f (θ) = θ^{2}$ and $g (θ) = \sin (2 θ)$ .

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Step 1.3.2.1

To apply the Chain Rule, set $u_{1}$ as $\sin (2 θ)$ .

$lim_{θ \to \frac{π}{2}} \frac{\frac{d}{d u_{1}} [{u_{1}}^{2}] \frac{d}{d θ} [\sin (2 θ)]}{\frac{d}{d θ} [1 - \sin^{2} (θ)]}$

Step 1.3.2.2

Differentiate using the Power Rule which states that $\frac{d}{d u_{1}} [{u_{1}}^{n}]$ is $n {u_{1}}^{n - 1}$ where $n = 2$ .

$lim_{θ \to \frac{π}{2}} \frac{2 u_{1} \frac{d}{d θ} [\sin (2 θ)]}{\frac{d}{d θ} [1 - \sin^{2} (θ)]}$

Step 1.3.2.3

Replace all occurrences of $u_{1}$ with $\sin (2 θ)$ .

$lim_{θ \to \frac{π}{2}} \frac{2 \sin (2 θ) \frac{d}{d θ} [\sin (2 θ)]}{\frac{d}{d θ} [1 - \sin^{2} (θ)]}$

Step 1.3.3

Differentiate using the chain rule, which states that $\frac{d}{d θ} [f (g (θ))]$ is $f' (g (θ)) g' (θ)$ where $f (θ) = \sin (θ)$ and $g (θ) = 2 θ$ .

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Step 1.3.3.1

To apply the Chain Rule, set $u_{2}$ as $2 θ$ .

$lim_{θ \to \frac{π}{2}} \frac{2 \sin (2 θ) (\frac{d}{d u_{2}} [\sin (u_{2})] \frac{d}{d θ} [2 θ])}{\frac{d}{d θ} [1 - \sin^{2} (θ)]}$

Step 1.3.3.2

The derivative of $\sin (u_{2})$ with respect to $u_{2}$ is $\cos (u_{2})$ .

$lim_{θ \to \frac{π}{2}} \frac{2 \sin (2 θ) (\cos (u_{2}) \frac{d}{d θ} [2 θ])}{\frac{d}{d θ} [1 - \sin^{2} (θ)]}$

Step 1.3.3.3

Replace all occurrences of $u_{2}$ with $2 θ$ .

$lim_{θ \to \frac{π}{2}} \frac{2 \sin (2 θ) (\cos (2 θ) \frac{d}{d θ} [2 θ])}{\frac{d}{d θ} [1 - \sin^{2} (θ)]}$

Step 1.3.4

Since $2$ is constant with respect to $θ$ , the derivative of $2 θ$ with respect to $θ$ is $2 \frac{d}{d θ} [θ]$ .

$lim_{θ \to \frac{π}{2}} \frac{2 \sin (2 θ) \cos (2 θ) (2 \frac{d}{d θ} [θ])}{\frac{d}{d θ} [1 - \sin^{2} (θ)]}$

Step 1.3.5

Multiply $2$ by $2$ .

$lim_{θ \to \frac{π}{2}} \frac{4 \sin (2 θ) \cos (2 θ) \frac{d}{d θ} [θ]}{\frac{d}{d θ} [1 - \sin^{2} (θ)]}$

Step 1.3.6

Differentiate using the Power Rule which states that $\frac{d}{d θ} [θ^{n}]$ is $n θ^{n - 1}$ where $n = 1$ .

$lim_{θ \to \frac{π}{2}} \frac{4 \sin (2 θ) \cos (2 θ) \cdot 1}{\frac{d}{d θ} [1 - \sin^{2} (θ)]}$

Step 1.3.7

Multiply $4$ by $1$ .

$lim_{θ \to \frac{π}{2}} \frac{4 \sin (2 θ) \cos (2 θ)}{\frac{d}{d θ} [1 - \sin^{2} (θ)]}$

Step 1.3.8

Reorder the factors of $4 \sin (2 θ) \cos (2 θ)$ .

$lim_{θ \to \frac{π}{2}} \frac{4 \cos (2 θ) \sin (2 θ)}{\frac{d}{d θ} [1 - \sin^{2} (θ)]}$

Step 1.3.9

By the Sum Rule, the derivative of $1 - \sin^{2} (θ)$ with respect to $θ$ is $\frac{d}{d θ} [1] + \frac{d}{d θ} [- \sin^{2} (θ)]$ .

$lim_{θ \to \frac{π}{2}} \frac{4 \cos (2 θ) \sin (2 θ)}{\frac{d}{d θ} [1] + \frac{d}{d θ} [- \sin^{2} (θ)]}$

Step 1.3.10

Since $1$ is constant with respect to $θ$ , the derivative of $1$ with respect to $θ$ is $0$ .

$lim_{θ \to \frac{π}{2}} \frac{4 \cos (2 θ) \sin (2 θ)}{0 + \frac{d}{d θ} [- \sin^{2} (θ)]}$

Step 1.3.11

Evaluate $\frac{d}{d θ} [- \sin^{2} (θ)]$ .

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Step 1.3.11.1

Since $- 1$ is constant with respect to $θ$ , the derivative of $- \sin^{2} (θ)$ with respect to $θ$ is $- \frac{d}{d θ} [\sin^{2} (θ)]$ .

$lim_{θ \to \frac{π}{2}} \frac{4 \cos (2 θ) \sin (2 θ)}{0 - \frac{d}{d θ} [\sin^{2} (θ)]}$

Step 1.3.11.2

Differentiate using the chain rule, which states that $\frac{d}{d θ} [f (g (θ))]$ is $f' (g (θ)) g' (θ)$ where $f (θ) = θ^{2}$ and $g (θ) = \sin (θ)$ .

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Step 1.3.11.2.1

To apply the Chain Rule, set $u$ as $\sin (θ)$ .

$lim_{θ \to \frac{π}{2}} \frac{4 \cos (2 θ) \sin (2 θ)}{0 - (\frac{d}{d u} [u^{2}] \frac{d}{d θ} [\sin (θ)])}$

Step 1.3.11.2.2

Differentiate using the Power Rule which states that $\frac{d}{d u} [u^{n}]$ is $n u^{n - 1}$ where $n = 2$ .

$lim_{θ \to \frac{π}{2}} \frac{4 \cos (2 θ) \sin (2 θ)}{0 - (2 u \frac{d}{d θ} [\sin (θ)])}$

Step 1.3.11.2.3

Replace all occurrences of $u$ with $\sin (θ)$ .

$lim_{θ \to \frac{π}{2}} \frac{4 \cos (2 θ) \sin (2 θ)}{0 - (2 \sin (θ) \frac{d}{d θ} [\sin (θ)])}$

Step 1.3.11.3

The derivative of $\sin (θ)$ with respect to $θ$ is $\cos (θ)$ .

$lim_{θ \to \frac{π}{2}} \frac{4 \cos (2 θ) \sin (2 θ)}{0 - (2 \sin (θ) \cos (θ))}$

Step 1.3.11.4

Multiply $2$ by $- 1$ .

$lim_{θ \to \frac{π}{2}} \frac{4 \cos (2 θ) \sin (2 θ)}{0 - 2 \sin (θ) \cos (θ)}$

Step 1.3.12

Simplify.

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Step 1.3.12.1

Subtract $2 \sin (θ) \cos (θ)$ from $0$ .

$lim_{θ \to \frac{π}{2}} \frac{4 \cos (2 θ) \sin (2 θ)}{- 2 \sin (θ) \cos (θ)}$

Step 1.3.12.2

Reorder the factors of $- 2 \sin (θ) \cos (θ)$ .

$lim_{θ \to \frac{π}{2}} \frac{4 \cos (2 θ) \sin (2 θ)}{- 2 \cos (θ) \sin (θ)}$

Step 1.4

Cancel the common factor of $4$ and $- 2$ .

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Step 1.4.1

Factor $2$ out of $4 \cos (2 θ) \sin (2 θ)$ .

$lim_{θ \to \frac{π}{2}} \frac{2 (2 \cos (2 θ) \sin (2 θ))}{- 2 \cos (θ) \sin (θ)}$

Step 1.4.2

Cancel the common factors.

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Step 1.4.2.1

Factor $2$ out of $- 2 \cos (θ) \sin (θ)$ .

$lim_{θ \to \frac{π}{2}} \frac{2 (2 \cos (2 θ) \sin (2 θ))}{2 (- \cos (θ) \sin (θ))}$

Step 1.4.2.2

Cancel the common factor.

$lim_{θ \to \frac{π}{2}} \frac{2 (2 \cos (2 θ) \sin (2 θ))}{2 (- \cos (θ) \sin (θ))}$

Step 1.4.2.3

Rewrite the expression.

$lim_{θ \to \frac{π}{2}} \frac{2 \cos (2 θ) \sin (2 θ)}{- \cos (θ) \sin (θ)}$

Step 2

Move the term $2$ outside of the limit because it is constant with respect to $θ$ .

$2 lim_{θ \to \frac{π}{2}} \frac{\cos (2 θ) \sin (2 θ)}{- \cos (θ) \sin (θ)}$

Step 3

Apply L'Hospital's rule.

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Step 3.1

Evaluate the limit of the numerator and the limit of the denominator.

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Step 3.1.1

Take the limit of the numerator and the limit of the denominator.

$2 \frac{lim_{θ \to \frac{π}{2}} \cos (2 θ) \sin (2 θ)}{lim_{θ \to \frac{π}{2}} - \cos (θ) \sin (θ)}$

Step 3.1.2

Evaluate the limit of the numerator.

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Step 3.1.2.1

Split the limit using the Product of Limits Rule on the limit as $θ$ approaches $\frac{π}{2}$ .

$2 \frac{lim_{θ \to \frac{π}{2}} \cos (2 θ) \cdot lim_{θ \to \frac{π}{2}} \sin (2 θ)}{lim_{θ \to \frac{π}{2}} - \cos (θ) \sin (θ)}$

Step 3.1.2.2

Move the limit inside the trig function because cosine is continuous.

$2 \frac{\cos (lim_{θ \to \frac{π}{2}} 2 θ) \cdot lim_{θ \to \frac{π}{2}} \sin (2 θ)}{lim_{θ \to \frac{π}{2}} - \cos (θ) \sin (θ)}$

Step 3.1.2.3

Move the term $2$ outside of the limit because it is constant with respect to $θ$ .

$2 \frac{\cos (2 lim_{θ \to \frac{π}{2}} θ) \cdot lim_{θ \to \frac{π}{2}} \sin (2 θ)}{lim_{θ \to \frac{π}{2}} - \cos (θ) \sin (θ)}$

Step 3.1.2.4

Move the limit inside the trig function because sine is continuous.

$2 \frac{\cos (2 lim_{θ \to \frac{π}{2}} θ) \cdot \sin (lim_{θ \to \frac{π}{2}} 2 θ)}{lim_{θ \to \frac{π}{2}} - \cos (θ) \sin (θ)}$

Step 3.1.2.5

Move the term $2$ outside of the limit because it is constant with respect to $θ$ .

$2 \frac{\cos (2 lim_{θ \to \frac{π}{2}} θ) \cdot \sin (2 lim_{θ \to \frac{π}{2}} θ)}{lim_{θ \to \frac{π}{2}} - \cos (θ) \sin (θ)}$

Step 3.1.2.6

Evaluate the limits by plugging in $\frac{π}{2}$ for all occurrences of $θ$ .

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Step 3.1.2.6.1

Evaluate the limit of $θ$ by plugging in $\frac{π}{2}$ for $θ$ .

$2 \frac{\cos (2 \frac{π}{2}) \cdot \sin (2 lim_{θ \to \frac{π}{2}} θ)}{lim_{θ \to \frac{π}{2}} - \cos (θ) \sin (θ)}$

Step 3.1.2.6.2

Evaluate the limit of $θ$ by plugging in $\frac{π}{2}$ for $θ$ .

$2 \frac{\cos (2 \frac{π}{2}) \cdot \sin (2 \frac{π}{2})}{lim_{θ \to \frac{π}{2}} - \cos (θ) \sin (θ)}$

Step 3.1.2.7

Simplify the answer.

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Step 3.1.2.7.1

Cancel the common factor of $2$ .

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Step 3.1.2.7.1.1

Cancel the common factor.

$2 \frac{\cos (2 \frac{π}{2}) \cdot \sin (2 \frac{π}{2})}{lim_{θ \to \frac{π}{2}} - \cos (θ) \sin (θ)}$

Step 3.1.2.7.1.2

Rewrite the expression.

$2 \frac{\cos (π) \cdot \sin (2 \frac{π}{2})}{lim_{θ \to \frac{π}{2}} - \cos (θ) \sin (θ)}$

Step 3.1.2.7.2

Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because cosine is negative in the second quadrant.

$2 \frac{- \cos (0) \cdot \sin (2 \frac{π}{2})}{lim_{θ \to \frac{π}{2}} - \cos (θ) \sin (θ)}$

Step 3.1.2.7.3

The exact value of $\cos (0)$ is $1$ .

$2 \frac{- 1 \cdot 1 \cdot \sin (2 \frac{π}{2})}{lim_{θ \to \frac{π}{2}} - \cos (θ) \sin (θ)}$

Step 3.1.2.7.4

Multiply $- 1$ by $1$ .

$2 \frac{- 1 \cdot \sin (2 \frac{π}{2})}{lim_{θ \to \frac{π}{2}} - \cos (θ) \sin (θ)}$

Step 3.1.2.7.5

Cancel the common factor of $2$ .

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Step 3.1.2.7.5.1

Cancel the common factor.

$2 \frac{- 1 \cdot \sin (2 \frac{π}{2})}{lim_{θ \to \frac{π}{2}} - \cos (θ) \sin (θ)}$

Step 3.1.2.7.5.2

Rewrite the expression.

$2 \frac{- 1 \cdot \sin (π)}{lim_{θ \to \frac{π}{2}} - \cos (θ) \sin (θ)}$

Step 3.1.2.7.6

Apply the reference angle by finding the angle with equivalent trig values in the first quadrant.

$2 \frac{- 1 \cdot \sin (0)}{lim_{θ \to \frac{π}{2}} - \cos (θ) \sin (θ)}$

Step 3.1.2.7.7

The exact value of $\sin (0)$ is $0$ .

$2 \frac{- 1 \cdot 0}{lim_{θ \to \frac{π}{2}} - \cos (θ) \sin (θ)}$

Step 3.1.2.7.8

Multiply $- 1$ by $0$ .

$2 \frac{0}{lim_{θ \to \frac{π}{2}} - \cos (θ) \sin (θ)}$

Step 3.1.3

Evaluate the limit of the denominator.

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Step 3.1.3.1

Move the term $- 1$ outside of the limit because it is constant with respect to $θ$ .

$2 \frac{0}{- lim_{θ \to \frac{π}{2}} \cos (θ) \sin (θ)}$

Step 3.1.3.2

Split the limit using the Product of Limits Rule on the limit as $θ$ approaches $\frac{π}{2}$ .

$2 \frac{0}{- lim_{θ \to \frac{π}{2}} \cos (θ) \cdot lim_{θ \to \frac{π}{2}} \sin (θ)}$

Step 3.1.3.3

Move the limit inside the trig function because cosine is continuous.

$2 \frac{0}{- \cos (lim_{θ \to \frac{π}{2}} θ) \cdot lim_{θ \to \frac{π}{2}} \sin (θ)}$

Step 3.1.3.4

Move the limit inside the trig function because sine is continuous.

$2 \frac{0}{- \cos (lim_{θ \to \frac{π}{2}} θ) \cdot \sin (lim_{θ \to \frac{π}{2}} θ)}$

Step 3.1.3.5

Evaluate the limits by plugging in $\frac{π}{2}$ for all occurrences of $θ$ .

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Step 3.1.3.5.1

Evaluate the limit of $θ$ by plugging in $\frac{π}{2}$ for $θ$ .

$2 \frac{0}{- \cos (\frac{π}{2}) \cdot \sin (lim_{θ \to \frac{π}{2}} θ)}$

Step 3.1.3.5.2

Evaluate the limit of $θ$ by plugging in $\frac{π}{2}$ for $θ$ .

$2 \frac{0}{- \cos (\frac{π}{2}) \cdot \sin (\frac{π}{2})}$

Step 3.1.3.6

Simplify the answer.

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Step 3.1.3.6.1

The exact value of $\cos (\frac{π}{2})$ is $0$ .

$2 \frac{0}{- 0 \cdot \sin (\frac{π}{2})}$

Step 3.1.3.6.2

Multiply $- 1$ by $0$ .

$2 \frac{0}{0 \cdot \sin (\frac{π}{2})}$

Step 3.1.3.6.3

The exact value of $\sin (\frac{π}{2})$ is $1$ .

$2 \frac{0}{0 \cdot 1}$

Step 3.1.3.6.4

Multiply $0$ by $1$ .

$2 (\frac{0}{0})$

Step 3.1.3.6.5

The expression contains a division by $0$ . The expression is undefined.

Undefined

$2 (\frac{0}{0})$

Step 3.1.3.7

The expression contains a division by $0$ . The expression is undefined.

Undefined

$2 (\frac{0}{0})$

Step 3.1.4

The expression contains a division by $0$ . The expression is undefined.

Undefined

$2 (\frac{0}{0})$

Step 3.2

Since $\frac{0}{0}$ is of indeterminate form, apply L'Hospital's Rule. L'Hospital's Rule states that the limit of a quotient of functions is equal to the limit of the quotient of their derivatives.

$lim_{θ \to \frac{π}{2}} \frac{\cos (2 θ) \sin (2 θ)}{- \cos (θ) \sin (θ)} = lim_{θ \to \frac{π}{2}} \frac{\frac{d}{d θ} [\cos (2 θ) \sin (2 θ)]}{\frac{d}{d θ} [- \cos (θ) \sin (θ)]}$

Step 3.3

Find the derivative of the numerator and denominator.

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Step 3.3.1

Differentiate the numerator and denominator.

$2 lim_{θ \to \frac{π}{2}} \frac{\frac{d}{d θ} [\cos (2 θ) \sin (2 θ)]}{\frac{d}{d θ} [- \cos (θ) \sin (θ)]}$

Step 3.3.2

Differentiate using the Product Rule which states that $\frac{d}{d θ} [f (θ) g (θ)]$ is $f (θ) \frac{d}{d θ} [g (θ)] + g (θ) \frac{d}{d θ} [f (θ)]$ where $f (θ) = \cos (2 θ)$ and $g (θ) = \sin (2 θ)$ .

$2 lim_{θ \to \frac{π}{2}} \frac{\cos (2 θ) \frac{d}{d θ} [\sin (2 θ)] + \sin (2 θ) \frac{d}{d θ} [\cos (2 θ)]}{\frac{d}{d θ} [- \cos (θ) \sin (θ)]}$

Step 3.3.3

Differentiate using the chain rule, which states that $\frac{d}{d θ} [f (g (θ))]$ is $f' (g (θ)) g' (θ)$ where $f (θ) = \sin (θ)$ and $g (θ) = 2 θ$ .

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Step 3.3.3.1

To apply the Chain Rule, set $u_{1}$ as $2 θ$ .

$2 lim_{θ \to \frac{π}{2}} \frac{\cos (2 θ) \frac{d}{d u_{1}} [\sin (u_{1})] \frac{d}{d θ} [2 θ] + \sin (2 θ) \frac{d}{d θ} [\cos (2 θ)]}{\frac{d}{d θ} [- \cos (θ) \sin (θ)]}$

Step 3.3.3.2

The derivative of $\sin (u_{1})$ with respect to $u_{1}$ is $\cos (u_{1})$ .

$2 lim_{θ \to \frac{π}{2}} \frac{\cos (2 θ) \cos (u_{1}) \frac{d}{d θ} [2 θ] + \sin (2 θ) \frac{d}{d θ} [\cos (2 θ)]}{\frac{d}{d θ} [- \cos (θ) \sin (θ)]}$

Step 3.3.3.3

Replace all occurrences of $u_{1}$ with $2 θ$ .

$2 lim_{θ \to \frac{π}{2}} \frac{\cos (2 θ) \cos (2 θ) \frac{d}{d θ} [2 θ] + \sin (2 θ) \frac{d}{d θ} [\cos (2 θ)]}{\frac{d}{d θ} [- \cos (θ) \sin (θ)]}$

Step 3.3.4

Raise $\cos (2 θ)$ to the power of $1$ .

$2 lim_{θ \to \frac{π}{2}} \frac{\cos^{1} (2 θ) \cos (2 θ) \frac{d}{d θ} [2 θ] + \sin (2 θ) \frac{d}{d θ} [\cos (2 θ)]}{\frac{d}{d θ} [- \cos (θ) \sin (θ)]}$

Step 3.3.5

Raise $\cos (2 θ)$ to the power of $1$ .

$2 lim_{θ \to \frac{π}{2}} \frac{\cos^{1} (2 θ) \cos^{1} (2 θ) \frac{d}{d θ} [2 θ] + \sin (2 θ) \frac{d}{d θ} [\cos (2 θ)]}{\frac{d}{d θ} [- \cos (θ) \sin (θ)]}$

Step 3.3.6

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$2 lim_{θ \to \frac{π}{2}} \frac{{\cos (2 θ)}^{1 + 1} \frac{d}{d θ} [2 θ] + \sin (2 θ) \frac{d}{d θ} [\cos (2 θ)]}{\frac{d}{d θ} [- \cos (θ) \sin (θ)]}$

Step 3.3.7

Add $1$ and $1$ .

$2 lim_{θ \to \frac{π}{2}} \frac{\cos^{2} (2 θ) \frac{d}{d θ} [2 θ] + \sin (2 θ) \frac{d}{d θ} [\cos (2 θ)]}{\frac{d}{d θ} [- \cos (θ) \sin (θ)]}$

Step 3.3.8

Since $2$ is constant with respect to $θ$ , the derivative of $2 θ$ with respect to $θ$ is $2 \frac{d}{d θ} [θ]$ .

$2 lim_{θ \to \frac{π}{2}} \frac{\cos^{2} (2 θ) \cdot 2 \frac{d}{d θ} [θ] + \sin (2 θ) \frac{d}{d θ} [\cos (2 θ)]}{\frac{d}{d θ} [- \cos (θ) \sin (θ)]}$

Step 3.3.9

Differentiate using the Power Rule which states that $\frac{d}{d θ} [θ^{n}]$ is $n θ^{n - 1}$ where $n = 1$ .

$2 lim_{θ \to \frac{π}{2}} \frac{\cos^{2} (2 θ) \cdot 2 \cdot 1 + \sin (2 θ) \frac{d}{d θ} [\cos (2 θ)]}{\frac{d}{d θ} [- \cos (θ) \sin (θ)]}$

Step 3.3.10

Multiply $2$ by $1$ .

$2 lim_{θ \to \frac{π}{2}} \frac{\cos^{2} (2 θ) \cdot 2 + \sin (2 θ) \frac{d}{d θ} [\cos (2 θ)]}{\frac{d}{d θ} [- \cos (θ) \sin (θ)]}$

Step 3.3.11

Move $2$ to the left of $\cos^{2} (2 θ)$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cdot \cos^{2} (2 θ) + \sin (2 θ) \frac{d}{d θ} [\cos (2 θ)]}{\frac{d}{d θ} [- \cos (θ) \sin (θ)]}$

Step 3.3.12

Differentiate using the chain rule, which states that $\frac{d}{d θ} [f (g (θ))]$ is $f' (g (θ)) g' (θ)$ where $f (θ) = \cos (θ)$ and $g (θ) = 2 θ$ .

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Step 3.3.12.1

To apply the Chain Rule, set $u_{2}$ as $2 θ$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) + \sin (2 θ) \frac{d}{d u_{2}} [\cos (u_{2})] \frac{d}{d θ} [2 θ]}{\frac{d}{d θ} [- \cos (θ) \sin (θ)]}$

Step 3.3.12.2

The derivative of $\cos (u_{2})$ with respect to $u_{2}$ is $- \sin (u_{2})$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) + \sin (2 θ) \cdot - 1 \sin (u_{2}) \frac{d}{d θ} [2 θ]}{\frac{d}{d θ} [- \cos (θ) \sin (θ)]}$

Step 3.3.12.3

Replace all occurrences of $u_{2}$ with $2 θ$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) + \sin (2 θ) \cdot - 1 \sin (2 θ) \frac{d}{d θ} [2 θ]}{\frac{d}{d θ} [- \cos (θ) \sin (θ)]}$

Step 3.3.13

Raise $\sin (2 θ)$ to the power of $1$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - \sin^{1} (2 θ) \sin (2 θ) \frac{d}{d θ} [2 θ]}{\frac{d}{d θ} [- \cos (θ) \sin (θ)]}$

Step 3.3.14

Raise $\sin (2 θ)$ to the power of $1$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - \sin^{1} (2 θ) \sin^{1} (2 θ) \frac{d}{d θ} [2 θ]}{\frac{d}{d θ} [- \cos (θ) \sin (θ)]}$

Step 3.3.15

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - {\sin (2 θ)}^{1 + 1} \frac{d}{d θ} [2 θ]}{\frac{d}{d θ} [- \cos (θ) \sin (θ)]}$

Step 3.3.16

Add $1$ and $1$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - \sin^{2} (2 θ) \frac{d}{d θ} [2 θ]}{\frac{d}{d θ} [- \cos (θ) \sin (θ)]}$

Step 3.3.17

Since $2$ is constant with respect to $θ$ , the derivative of $2 θ$ with respect to $θ$ is $2 \frac{d}{d θ} [θ]$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - \sin^{2} (2 θ) \cdot 2 \frac{d}{d θ} [θ]}{\frac{d}{d θ} [- \cos (θ) \sin (θ)]}$

Step 3.3.18

Multiply $2$ by $- 1$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ) \frac{d}{d θ} [θ]}{\frac{d}{d θ} [- \cos (θ) \sin (θ)]}$

Step 3.3.19

Differentiate using the Power Rule which states that $\frac{d}{d θ} [θ^{n}]$ is $n θ^{n - 1}$ where $n = 1$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ) \cdot 1}{\frac{d}{d θ} [- \cos (θ) \sin (θ)]}$

Step 3.3.20

Multiply $- 2$ by $1$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{\frac{d}{d θ} [- \cos (θ) \sin (θ)]}$

Step 3.3.21

Since $- 1$ is constant with respect to $θ$ , the derivative of $- \cos (θ) \sin (θ)$ with respect to $θ$ is $- \frac{d}{d θ} [\cos (θ) \sin (θ)]$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{- \frac{d}{d θ} [\cos (θ) \sin (θ)]}$

Step 3.3.22

Differentiate using the Product Rule which states that $\frac{d}{d θ} [f (θ) g (θ)]$ is $f (θ) \frac{d}{d θ} [g (θ)] + g (θ) \frac{d}{d θ} [f (θ)]$ where $f (θ) = \cos (θ)$ and $g (θ) = \sin (θ)$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{- (\cos (θ) \frac{d}{d θ} [\sin (θ)] + \sin (θ) \frac{d}{d θ} [\cos (θ)])}$

Step 3.3.23

The derivative of $\sin (θ)$ with respect to $θ$ is $\cos (θ)$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{- (\cos (θ) \cos (θ) + \sin (θ) \frac{d}{d θ} [\cos (θ)])}$

Step 3.3.24

Raise $\cos (θ)$ to the power of $1$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{- (\cos^{1} (θ) \cos (θ) + \sin (θ) \frac{d}{d θ} [\cos (θ)])}$

Step 3.3.25

Raise $\cos (θ)$ to the power of $1$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{- (\cos^{1} (θ) \cos^{1} (θ) + \sin (θ) \frac{d}{d θ} [\cos (θ)])}$

Step 3.3.26

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{- ({\cos (θ)}^{1 + 1} + \sin (θ) \frac{d}{d θ} [\cos (θ)])}$

Step 3.3.27

Add $1$ and $1$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{- (\cos^{2} (θ) + \sin (θ) \frac{d}{d θ} [\cos (θ)])}$

Step 3.3.28

The derivative of $\cos (θ)$ with respect to $θ$ is $- \sin (θ)$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{- (\cos^{2} (θ) + \sin (θ) \cdot - 1 \sin (θ))}$

Step 3.3.29

Raise $\sin (θ)$ to the power of $1$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{- (\cos^{2} (θ) - \sin^{1} (θ) \sin (θ))}$

Step 3.3.30

Raise $\sin (θ)$ to the power of $1$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{- (\cos^{2} (θ) - \sin^{1} (θ) \sin^{1} (θ))}$

Step 3.3.31

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{- (\cos^{2} (θ) - {\sin (θ)}^{1 + 1})}$

Step 3.3.32

Add $1$ and $1$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{- (\cos^{2} (θ) - \sin^{2} (θ))}$

Step 3.3.33

Simplify.

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Step 3.3.33.1

Apply the distributive property.

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{- \cos^{2} (θ) - - 1 \sin^{2} (θ)}$

Step 3.3.33.2

Combine terms.

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Step 3.3.33.2.1

Multiply $- 1$ by $- 1$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{- \cos^{2} (θ) + 1 \sin^{2} (θ)}$

Step 3.3.33.2.2

Multiply $\sin^{2} (θ)$ by $1$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{- \cos^{2} (θ) + \sin^{2} (θ)}$

Step 3.3.33.3

Reorder $- \cos^{2} (θ)$ and $\sin^{2} (θ)$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{\sin^{2} (θ) - \cos^{2} (θ)}$

Step 3.3.33.4

Since both terms are perfect squares, factor using the difference of squares formula, $a^{2} - b^{2} = (a + b) (a - b)$ where $a = \sin (θ)$ and $b = \cos (θ)$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{(\sin (θ) + \cos (θ)) (\sin (θ) - \cos (θ))}$

Step 3.3.33.5

Expand $(\sin (θ) + \cos (θ)) (\sin (θ) - \cos (θ))$ using the FOIL Method.

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Step 3.3.33.5.1

Apply the distributive property.

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{\sin (θ) (\sin (θ) - \cos (θ)) + \cos (θ) (\sin (θ) - \cos (θ))}$

Step 3.3.33.5.2

Apply the distributive property.

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{\sin (θ) \sin (θ) + \sin (θ) \cdot - 1 \cos (θ) + \cos (θ) (\sin (θ) - \cos (θ))}$

Step 3.3.33.5.3

Apply the distributive property.

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{\sin (θ) \sin (θ) + \sin (θ) \cdot - 1 \cos (θ) + \cos (θ) \sin (θ) + \cos (θ) \cdot - 1 \cos (θ)}$

Step 3.3.33.6

Combine the opposite terms in $\sin (θ) \sin (θ) + \sin (θ) (- \cos (θ)) + \cos (θ) \sin (θ) + \cos (θ) (- \cos (θ))$ .

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Step 3.3.33.6.1

Reorder the factors in the terms $\sin (θ) (- \cos (θ))$ and $\cos (θ) \sin (θ)$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{\sin (θ) \sin (θ) - \cos (θ) \sin (θ) + \cos (θ) \sin (θ) + \cos (θ) \cdot - 1 \cos (θ)}$

Step 3.3.33.6.2

Add $- \cos (θ) \sin (θ)$ and $\cos (θ) \sin (θ)$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{\sin (θ) \sin (θ) + 0 + \cos (θ) \cdot - 1 \cos (θ)}$

Step 3.3.33.6.3

Add $\sin (θ) \sin (θ)$ and $0$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{\sin (θ) \sin (θ) + \cos (θ) \cdot - 1 \cos (θ)}$

Step 3.3.33.7

Simplify each term.

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Step 3.3.33.7.1

Multiply $\sin (θ) \sin (θ)$ .

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Step 3.3.33.7.1.1

Raise $\sin (θ)$ to the power of $1$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{\sin^{1} (θ) \sin (θ) + \cos (θ) \cdot - 1 \cos (θ)}$

Step 3.3.33.7.1.2

Raise $\sin (θ)$ to the power of $1$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{\sin^{1} (θ) \sin^{1} (θ) + \cos (θ) \cdot - 1 \cos (θ)}$

Step 3.3.33.7.1.3

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{{\sin (θ)}^{1 + 1} + \cos (θ) \cdot - 1 \cos (θ)}$

Step 3.3.33.7.1.4

Add $1$ and $1$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{\sin^{2} (θ) + \cos (θ) \cdot - 1 \cos (θ)}$

Step 3.3.33.7.2

Rewrite using the commutative property of multiplication.

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{\sin^{2} (θ) - \cos (θ) \cos (θ)}$

Step 3.3.33.7.3

Multiply $- \cos (θ) \cos (θ)$ .

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Step 3.3.33.7.3.1

Raise $\cos (θ)$ to the power of $1$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{\sin^{2} (θ) - \cos^{1} (θ) \cos (θ)}$

Step 3.3.33.7.3.2

Raise $\cos (θ)$ to the power of $1$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{\sin^{2} (θ) - \cos^{1} (θ) \cos^{1} (θ)}$

Step 3.3.33.7.3.3

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{\sin^{2} (θ) - {\cos (θ)}^{1 + 1}}$

Step 3.3.33.7.3.4

Add $1$ and $1$ .

$2 lim_{θ \to \frac{π}{2}} \frac{2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{\sin^{2} (θ) - \cos^{2} (θ)}$

Step 4

Evaluate the limit.

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Step 4.1

Split the limit using the Limits Quotient Rule on the limit as $θ$ approaches $\frac{π}{2}$ .

$2 \frac{lim_{θ \to \frac{π}{2}} 2 \cos^{2} (2 θ) - 2 \sin^{2} (2 θ)}{lim_{θ \to \frac{π}{2}} \sin^{2} (θ) - \cos^{2} (θ)}$

Step 4.2

Split the limit using the Sum of Limits Rule on the limit as $θ$ approaches $\frac{π}{2}$ .

$2 \frac{lim_{θ \to \frac{π}{2}} 2 \cos^{2} (2 θ) - lim_{θ \to \frac{π}{2}} 2 \sin^{2} (2 θ)}{lim_{θ \to \frac{π}{2}} \sin^{2} (θ) - \cos^{2} (θ)}$

Step 4.3

Move the term $2$ outside of the limit because it is constant with respect to $θ$ .

$2 \frac{2 lim_{θ \to \frac{π}{2}} \cos^{2} (2 θ) - lim_{θ \to \frac{π}{2}} 2 \sin^{2} (2 θ)}{lim_{θ \to \frac{π}{2}} \sin^{2} (θ) - \cos^{2} (θ)}$

Step 4.4

Move the exponent $2$ from $\cos^{2} (2 θ)$ outside the limit using the Limits Power Rule.

$2 \frac{2 {(lim_{θ \to \frac{π}{2}} \cos (2 θ))}^{2} - lim_{θ \to \frac{π}{2}} 2 \sin^{2} (2 θ)}{lim_{θ \to \frac{π}{2}} \sin^{2} (θ) - \cos^{2} (θ)}$

Step 4.5

Move the limit inside the trig function because cosine is continuous.

$2 \frac{2 \cos^{2} (lim_{θ \to \frac{π}{2}} 2 θ) - lim_{θ \to \frac{π}{2}} 2 \sin^{2} (2 θ)}{lim_{θ \to \frac{π}{2}} \sin^{2} (θ) - \cos^{2} (θ)}$

Step 4.6

Move the term $2$ outside of the limit because it is constant with respect to $θ$ .

$2 \frac{2 \cos^{2} (2 lim_{θ \to \frac{π}{2}} θ) - lim_{θ \to \frac{π}{2}} 2 \sin^{2} (2 θ)}{lim_{θ \to \frac{π}{2}} \sin^{2} (θ) - \cos^{2} (θ)}$

Step 4.7

Move the term $2$ outside of the limit because it is constant with respect to $θ$ .

$2 \frac{2 \cos^{2} (2 lim_{θ \to \frac{π}{2}} θ) - 2 lim_{θ \to \frac{π}{2}} \sin^{2} (2 θ)}{lim_{θ \to \frac{π}{2}} \sin^{2} (θ) - \cos^{2} (θ)}$

Step 4.8

Move the exponent $2$ from $\sin^{2} (2 θ)$ outside the limit using the Limits Power Rule.

$2 \frac{2 \cos^{2} (2 lim_{θ \to \frac{π}{2}} θ) - 2 {(lim_{θ \to \frac{π}{2}} \sin (2 θ))}^{2}}{lim_{θ \to \frac{π}{2}} \sin^{2} (θ) - \cos^{2} (θ)}$

Step 4.9

Move the limit inside the trig function because sine is continuous.

$2 \frac{2 \cos^{2} (2 lim_{θ \to \frac{π}{2}} θ) - 2 \sin^{2} (lim_{θ \to \frac{π}{2}} 2 θ)}{lim_{θ \to \frac{π}{2}} \sin^{2} (θ) - \cos^{2} (θ)}$

Step 4.10

Move the term $2$ outside of the limit because it is constant with respect to $θ$ .

$2 \frac{2 \cos^{2} (2 lim_{θ \to \frac{π}{2}} θ) - 2 \sin^{2} (2 lim_{θ \to \frac{π}{2}} θ)}{lim_{θ \to \frac{π}{2}} \sin^{2} (θ) - \cos^{2} (θ)}$

Step 4.11

Split the limit using the Sum of Limits Rule on the limit as $θ$ approaches $\frac{π}{2}$ .

$2 \frac{2 \cos^{2} (2 lim_{θ \to \frac{π}{2}} θ) - 2 \sin^{2} (2 lim_{θ \to \frac{π}{2}} θ)}{lim_{θ \to \frac{π}{2}} \sin^{2} (θ) - lim_{θ \to \frac{π}{2}} \cos^{2} (θ)}$

Step 4.12

Move the exponent $2$ from $\sin^{2} (θ)$ outside the limit using the Limits Power Rule.

$2 \frac{2 \cos^{2} (2 lim_{θ \to \frac{π}{2}} θ) - 2 \sin^{2} (2 lim_{θ \to \frac{π}{2}} θ)}{{(lim_{θ \to \frac{π}{2}} \sin (θ))}^{2} - lim_{θ \to \frac{π}{2}} \cos^{2} (θ)}$

Step 4.13

Move the limit inside the trig function because sine is continuous.

$2 \frac{2 \cos^{2} (2 lim_{θ \to \frac{π}{2}} θ) - 2 \sin^{2} (2 lim_{θ \to \frac{π}{2}} θ)}{\sin^{2} (lim_{θ \to \frac{π}{2}} θ) - lim_{θ \to \frac{π}{2}} \cos^{2} (θ)}$

Step 4.14

Move the exponent $2$ from $\cos^{2} (θ)$ outside the limit using the Limits Power Rule.

$2 \frac{2 \cos^{2} (2 lim_{θ \to \frac{π}{2}} θ) - 2 \sin^{2} (2 lim_{θ \to \frac{π}{2}} θ)}{\sin^{2} (lim_{θ \to \frac{π}{2}} θ) - {(lim_{θ \to \frac{π}{2}} \cos (θ))}^{2}}$

Step 4.15

Move the limit inside the trig function because cosine is continuous.

$2 \frac{2 \cos^{2} (2 lim_{θ \to \frac{π}{2}} θ) - 2 \sin^{2} (2 lim_{θ \to \frac{π}{2}} θ)}{\sin^{2} (lim_{θ \to \frac{π}{2}} θ) - \cos^{2} (lim_{θ \to \frac{π}{2}} θ)}$

Step 5

Evaluate the limits by plugging in $\frac{π}{2}$ for all occurrences of $θ$ .

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Step 5.1

Evaluate the limit of $θ$ by plugging in $\frac{π}{2}$ for $θ$ .

$2 \frac{2 \cos^{2} (2 \frac{π}{2}) - 2 \sin^{2} (2 lim_{θ \to \frac{π}{2}} θ)}{\sin^{2} (lim_{θ \to \frac{π}{2}} θ) - \cos^{2} (lim_{θ \to \frac{π}{2}} θ)}$

Step 5.2

Evaluate the limit of $θ$ by plugging in $\frac{π}{2}$ for $θ$ .

$2 \frac{2 \cos^{2} (2 \frac{π}{2}) - 2 \sin^{2} (2 \frac{π}{2})}{\sin^{2} (lim_{θ \to \frac{π}{2}} θ) - \cos^{2} (lim_{θ \to \frac{π}{2}} θ)}$

Step 5.3

Evaluate the limit of $θ$ by plugging in $\frac{π}{2}$ for $θ$ .

$2 \frac{2 \cos^{2} (2 \frac{π}{2}) - 2 \sin^{2} (2 \frac{π}{2})}{\sin^{2} (\frac{π}{2}) - \cos^{2} (lim_{θ \to \frac{π}{2}} θ)}$

Step 5.4

Evaluate the limit of $θ$ by plugging in $\frac{π}{2}$ for $θ$ .

$2 \frac{2 \cos^{2} (2 \frac{π}{2}) - 2 \sin^{2} (2 \frac{π}{2})}{\sin^{2} (\frac{π}{2}) - \cos^{2} (\frac{π}{2})}$

Step 6

Simplify the answer.

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Step 6.1

Simplify the numerator.

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Step 6.1.1

Cancel the common factor of $2$ .

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Step 6.1.1.1

Cancel the common factor.

$2 \frac{2 \cos^{2} (2 \frac{π}{2}) - 2 \sin^{2} (2 \frac{π}{2})}{\sin^{2} (\frac{π}{2}) - \cos^{2} (\frac{π}{2})}$

Step 6.1.1.2

Rewrite the expression.

$2 \frac{2 \cos^{2} (π) - 2 \sin^{2} (2 \frac{π}{2})}{\sin^{2} (\frac{π}{2}) - \cos^{2} (\frac{π}{2})}$

Step 6.1.2

Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because cosine is negative in the second quadrant.

$2 \frac{2 {(- \cos (0))}^{2} - 2 \sin^{2} (2 \frac{π}{2})}{\sin^{2} (\frac{π}{2}) - \cos^{2} (\frac{π}{2})}$

Step 6.1.3

The exact value of $\cos (0)$ is $1$ .

$2 \frac{2 {(- 1 \cdot 1)}^{2} - 2 \sin^{2} (2 \frac{π}{2})}{\sin^{2} (\frac{π}{2}) - \cos^{2} (\frac{π}{2})}$

Step 6.1.4

Multiply $- 1$ by $1$ .

$2 \frac{2 {(- 1)}^{2} - 2 \sin^{2} (2 \frac{π}{2})}{\sin^{2} (\frac{π}{2}) - \cos^{2} (\frac{π}{2})}$

Step 6.1.5

Raise $- 1$ to the power of $2$ .

$2 \frac{2 \cdot 1 - 2 \sin^{2} (2 \frac{π}{2})}{\sin^{2} (\frac{π}{2}) - \cos^{2} (\frac{π}{2})}$

Step 6.1.6

Multiply $2$ by $1$ .

$2 \frac{2 - 2 \sin^{2} (2 \frac{π}{2})}{\sin^{2} (\frac{π}{2}) - \cos^{2} (\frac{π}{2})}$

Step 6.1.7

Cancel the common factor of $2$ .

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Step 6.1.7.1

Cancel the common factor.

$2 \frac{2 - 2 \sin^{2} (2 \frac{π}{2})}{\sin^{2} (\frac{π}{2}) - \cos^{2} (\frac{π}{2})}$

Step 6.1.7.2

Rewrite the expression.

$2 \frac{2 - 2 \sin^{2} (π)}{\sin^{2} (\frac{π}{2}) - \cos^{2} (\frac{π}{2})}$

Step 6.1.8

Apply the reference angle by finding the angle with equivalent trig values in the first quadrant.

$2 \frac{2 - 2 \sin^{2} (0)}{\sin^{2} (\frac{π}{2}) - \cos^{2} (\frac{π}{2})}$

Step 6.1.9

The exact value of $\sin (0)$ is $0$ .

$2 \frac{2 - 2 \cdot 0^{2}}{\sin^{2} (\frac{π}{2}) - \cos^{2} (\frac{π}{2})}$

Step 6.1.10

Raising $0$ to any positive power yields $0$ .

$2 \frac{2 - 2 \cdot 0}{\sin^{2} (\frac{π}{2}) - \cos^{2} (\frac{π}{2})}$

Step 6.1.11

Multiply $- 2$ by $0$ .

$2 \frac{2 + 0}{\sin^{2} (\frac{π}{2}) - \cos^{2} (\frac{π}{2})}$

Step 6.1.12

Add $2$ and $0$ .

$2 \frac{2}{\sin^{2} (\frac{π}{2}) - \cos^{2} (\frac{π}{2})}$

Step 6.2

Simplify the denominator.

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Step 6.2.1

The exact value of $\sin (\frac{π}{2})$ is $1$ .

$2 \frac{2}{1^{2} - \cos^{2} (\frac{π}{2})}$

Step 6.2.2

One to any power is one.

$2 \frac{2}{1 - \cos^{2} (\frac{π}{2})}$

Step 6.2.3

The exact value of $\cos (\frac{π}{2})$ is $0$ .

$2 \frac{2}{1 - 0^{2}}$

Step 6.2.4

Raising $0$ to any positive power yields $0$ .

$2 \frac{2}{1 - 0}$

Step 6.2.5

Multiply $- 1$ by $0$ .

$2 \frac{2}{1 + 0}$

Step 6.2.6

Add $1$ and $0$ .

$2 (\frac{2}{1})$

Step 6.3

Divide $2$ by $1$ .

$2 \cdot 2$

Step 6.4

Multiply $2$ by $2$ .

$4$