Trigonometry Examples

$2 \cos (x) + 3 \cos (- x)$

Step 1

Since $\cos (- x)$ is an even function, rewrite $\cos (- x)$ as $\cos (x)$ .

$2 \cos (x) + 3 \cos (x)$

Step 2

Add $2 \cos (x)$ and $3 \cos (x)$ .

$5 \cos (x)$