Trigonometry Examples

$\cos (2 \cdot 45) = 2 \cos (45)$

Step 1

Simplify $\cos (2 \cdot 45)$ .

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Step 1.1

Multiply $2$ by $45$ .

$\cos (90) = 2 \cos (45)$

Step 1.2

The exact value of $\cos (90)$ is $0$ .

$0 = 2 \cos (45)$

Step 2

Simplify $2 \cos (45)$ .

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Step 2.1

The exact value of $\cos (45)$ is $\frac{\sqrt{2}}{2}$ .

$0 = 2 \frac{\sqrt{2}}{2}$

Step 2.2

Cancel the common factor of $2$ .

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Step 2.2.1

Cancel the common factor.

$0 = 2 \frac{\sqrt{2}}{2}$

Step 2.2.2

Rewrite the expression.

$0 = \sqrt{2}$

Step 3