CPM Homework Help : PC Problem 9-105

Hint:

Use the double angle formula:
2cosx · sinx = sin2x

Step 1:

4(2cosx · sinx) = 2

Step 2:

4(sin2x) = 2

Step 3:

$\text{sin}2x=\frac{1}{2}$

Step 4:

$2x=\frac{\pi }{6}+2\pi n,\therefore x=\frac{\pi }{12}+\pi n$

$2x=\frac{5\pi }{6}+2\pi n,\therefore x=\frac{5\pi }{12}+\pi n$