CPM Homework Help : PC Problem 11-59

Show that $4 \cos (x + \frac { \pi } { 3 }) = 2 \cos x − 2 \sqrt 3 \sin x$ .

Hint:

Use the Angle Sum Identity.

Step 1:

$4\left( \cos(\textit{x})\cos\left( \frac{\pi}{3} \right) - \sin(\textit{x})\sin\left( \frac{\pi}{3} \right)\right) =$

Step 2:

Substitute the exact values for sine and cosine of $\frac{π}{3}$ . Then simplify.