Trigonometry Examples

$2 \cos (π)$

Step 1

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.

$2 (- \cos (0))$

Step 2

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

$2 (- 1 \cdot 1)$

Step 3

Multiply $2 (- 1 \cdot 1)$ .

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Step 3.1

Multiply $- 1$ by $1$ .

$2 \cdot - 1$

Step 3.2

Multiply $2$ by $- 1$ .

$- 2$