Trigonometry Examples

$\frac{\sec (x) - \csc (x)}{\sec (x) + \csc (x)} = \frac{1 - \cot (x)}{1 + \cot (x)}$

Step 1

Subtract $\frac{1 - \cot (x)}{1 + \cot (x)}$ from both sides of the equation.

$\frac{\sec (x) - \csc (x)}{\sec (x) + \csc (x)} - \frac{1 - \cot (x)}{1 + \cot (x)} = 0$

Step 2

Simplify $\frac{\sec (x) - \csc (x)}{\sec (x) + \csc (x)} - \frac{1 - \cot (x)}{1 + \cot (x)}$ .

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Step 2.1

To write $\frac{\sec (x) - \csc (x)}{\sec (x) + \csc (x)}$ as a fraction with a common denominator, multiply by $\frac{1 + \cot (x)}{1 + \cot (x)}$ .

$\frac{\sec (x) - \csc (x)}{\sec (x) + \csc (x)} \cdot \frac{1 + \cot (x)}{1 + \cot (x)} - \frac{1 - \cot (x)}{1 + \cot (x)} = 0$

Step 2.2

To write $- \frac{1 - \cot (x)}{1 + \cot (x)}$ as a fraction with a common denominator, multiply by $\frac{\sec (x) + \csc (x)}{\sec (x) + \csc (x)}$ .

$\frac{\sec (x) - \csc (x)}{\sec (x) + \csc (x)} \cdot \frac{1 + \cot (x)}{1 + \cot (x)} - \frac{1 - \cot (x)}{1 + \cot (x)} \cdot \frac{\sec (x) + \csc (x)}{\sec (x) + \csc (x)} = 0$

Step 2.3

Write each expression with a common denominator of $(\sec (x) + \csc (x)) (1 + \cot (x))$ , by multiplying each by an appropriate factor of $1$ .

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Step 2.3.1

Multiply $\frac{\sec (x) - \csc (x)}{\sec (x) + \csc (x)}$ by $\frac{1 + \cot (x)}{1 + \cot (x)}$ .

$\frac{(\sec (x) - \csc (x)) (1 + \cot (x))}{(\sec (x) + \csc (x)) (1 + \cot (x))} - \frac{1 - \cot (x)}{1 + \cot (x)} \cdot \frac{\sec (x) + \csc (x)}{\sec (x) + \csc (x)} = 0$

Step 2.3.2

Multiply $\frac{1 - \cot (x)}{1 + \cot (x)}$ by $\frac{\sec (x) + \csc (x)}{\sec (x) + \csc (x)}$ .

$\frac{(\sec (x) - \csc (x)) (1 + \cot (x))}{(\sec (x) + \csc (x)) (1 + \cot (x))} - \frac{(1 - \cot (x)) (\sec (x) + \csc (x))}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.3.3

Reorder the factors of $(\sec (x) + \csc (x)) (1 + \cot (x))$ .

$\frac{(\sec (x) - \csc (x)) (1 + \cot (x))}{(1 + \cot (x)) (\sec (x) + \csc (x))} - \frac{(1 - \cot (x)) (\sec (x) + \csc (x))}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.4

Combine the numerators over the common denominator.

$\frac{(\sec (x) - \csc (x)) (1 + \cot (x)) - (1 - \cot (x)) (\sec (x) + \csc (x))}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5

Simplify the numerator.

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Step 2.5.1

Expand $(\sec (x) - \csc (x)) (1 + \cot (x))$ using the FOIL Method.

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Step 2.5.1.1

Apply the distributive property.

$\frac{\sec (x) (1 + \cot (x)) - \csc (x) (1 + \cot (x)) - (1 - \cot (x)) (\sec (x) + \csc (x))}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.1.2

Apply the distributive property.

$\frac{\sec (x) \cdot 1 + \sec (x) \cot (x) - \csc (x) (1 + \cot (x)) - (1 - \cot (x)) (\sec (x) + \csc (x))}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.1.3

Apply the distributive property.

$\frac{\sec (x) \cdot 1 + \sec (x) \cot (x) - \csc (x) \cdot 1 - \csc (x) \cot (x) - (1 - \cot (x)) (\sec (x) + \csc (x))}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.2

Simplify and combine like terms.

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Step 2.5.2.1

Simplify each term.

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Step 2.5.2.1.1

Multiply $\sec (x)$ by $1$ .

$\frac{\sec (x) + \sec (x) \cot (x) - \csc (x) \cdot 1 - \csc (x) \cot (x) - (1 - \cot (x)) (\sec (x) + \csc (x))}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.2.1.2

Rewrite in terms of sines and cosines, then cancel the common factors.

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Step 2.5.2.1.2.1

Reorder $\sec (x)$ and $\cot (x)$ .

$\frac{\sec (x) + \cot (x) \sec (x) - \csc (x) \cdot 1 - \csc (x) \cot (x) - (1 - \cot (x)) (\sec (x) + \csc (x))}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.2.1.2.2

Rewrite $\sec (x) \cot (x)$ in terms of sines and cosines.

$\frac{\sec (x) + \frac{\cos (x)}{\sin (x)} \cdot \frac{1}{\cos (x)} - \csc (x) \cdot 1 - \csc (x) \cot (x) - (1 - \cot (x)) (\sec (x) + \csc (x))}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.2.1.2.3

Cancel the common factors.

$\frac{\sec (x) + \frac{1}{\sin (x)} - \csc (x) \cdot 1 - \csc (x) \cot (x) - (1 - \cot (x)) (\sec (x) + \csc (x))}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.2.1.3

Convert from $\frac{1}{\sin (x)}$ to $\csc (x)$ .

$\frac{\sec (x) + \csc (x) - \csc (x) \cdot 1 - \csc (x) \cot (x) - (1 - \cot (x)) (\sec (x) + \csc (x))}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.2.1.4

Multiply $- 1$ by $1$ .

$\frac{\sec (x) + \csc (x) - \csc (x) - \csc (x) \cot (x) - (1 - \cot (x)) (\sec (x) + \csc (x))}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.2.2

Subtract $\csc (x)$ from $\csc (x)$ .

$\frac{\sec (x) + 0 - \csc (x) \cot (x) - (1 - \cot (x)) (\sec (x) + \csc (x))}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.2.3

Add $\sec (x)$ and $0$ .

$\frac{\sec (x) - \csc (x) \cot (x) - (1 - \cot (x)) (\sec (x) + \csc (x))}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.3

Apply the distributive property.

$\frac{\sec (x) - \csc (x) \cot (x) + (- 1 \cdot 1 - - \cot (x)) (\sec (x) + \csc (x))}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.4

Multiply $- 1$ by $1$ .

$\frac{\sec (x) - \csc (x) \cot (x) + (- 1 - - \cot (x)) (\sec (x) + \csc (x))}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.5

Multiply $- - \cot (x)$ .

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Step 2.5.5.1

Multiply $- 1$ by $- 1$ .

$\frac{\sec (x) - \csc (x) \cot (x) + (- 1 + 1 \cot (x)) (\sec (x) + \csc (x))}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.5.2

Multiply $\cot (x)$ by $1$ .

$\frac{\sec (x) - \csc (x) \cot (x) + (- 1 + \cot (x)) (\sec (x) + \csc (x))}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.6

Expand $(- 1 + \cot (x)) (\sec (x) + \csc (x))$ using the FOIL Method.

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Step 2.5.6.1

Apply the distributive property.

$\frac{\sec (x) - \csc (x) \cot (x) - 1 (\sec (x) + \csc (x)) + \cot (x) (\sec (x) + \csc (x))}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.6.2

Apply the distributive property.

$\frac{\sec (x) - \csc (x) \cot (x) - 1 \sec (x) - 1 \csc (x) + \cot (x) (\sec (x) + \csc (x))}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.6.3

Apply the distributive property.

$\frac{\sec (x) - \csc (x) \cot (x) - 1 \sec (x) - 1 \csc (x) + \cot (x) \sec (x) + \cot (x) \csc (x)}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.7

Simplify and combine like terms.

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Step 2.5.7.1

Simplify each term.

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Step 2.5.7.1.1

Rewrite $- 1 \sec (x)$ as $- \sec (x)$ .

$\frac{\sec (x) - \csc (x) \cot (x) - \sec (x) - 1 \csc (x) + \cot (x) \sec (x) + \cot (x) \csc (x)}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.7.1.2

Rewrite $- 1 \csc (x)$ as $- \csc (x)$ .

$\frac{\sec (x) - \csc (x) \cot (x) - \sec (x) - \csc (x) + \cot (x) \sec (x) + \cot (x) \csc (x)}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.7.1.3

Rewrite in terms of sines and cosines, then cancel the common factors.

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Step 2.5.7.1.3.1

Rewrite $\cot (x) \sec (x)$ in terms of sines and cosines.

$\frac{\sec (x) - \csc (x) \cot (x) - \sec (x) - \csc (x) + \frac{\cos (x)}{\sin (x)} \cdot \frac{1}{\cos (x)} + \cot (x) \csc (x)}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.7.1.3.2

Cancel the common factors.

$\frac{\sec (x) - \csc (x) \cot (x) - \sec (x) - \csc (x) + \frac{1}{\sin (x)} + \cot (x) \csc (x)}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.7.1.4

Convert from $\frac{1}{\sin (x)}$ to $\csc (x)$ .

$\frac{\sec (x) - \csc (x) \cot (x) - \sec (x) - \csc (x) + \csc (x) + \cot (x) \csc (x)}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.7.2

Add $- \csc (x)$ and $\csc (x)$ .

$\frac{\sec (x) - \csc (x) \cot (x) - \sec (x) + 0 + \cot (x) \csc (x)}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.7.3

Add $- \sec (x)$ and $0$ .

$\frac{\sec (x) - \csc (x) \cot (x) - \sec (x) + \cot (x) \csc (x)}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.8

Subtract $\sec (x)$ from $\sec (x)$ .

$\frac{- \csc (x) \cot (x) + 0 + \cot (x) \csc (x)}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.9

Add $- \csc (x) \cot (x)$ and $0$ .

$\frac{- \csc (x) \cot (x) + \cot (x) \csc (x)}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.10

Reorder the factors of $- \csc (x) \cot (x)$ .

$\frac{- \cot (x) \csc (x) + \cot (x) \csc (x)}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.5.11

Add $- \cot (x) \csc (x)$ and $\cot (x) \csc (x)$ .

$\frac{0}{(1 + \cot (x)) (\sec (x) + \csc (x))} = 0$

Step 2.6

Divide $0$ by $(1 + \cot (x)) (\sec (x) + \csc (x))$ .

$0 = 0$

Step 3

The domain of the expression is all real numbers except where the expression is undefined. In this case, there is no real number that makes the expression undefined.