Question 971858
 3 + cos 2x = 7/2

cos 2x=1/2  subtracting 3 or 6/2.

cos 2x= 1-2 sin^2 x =1/2

subtract 1 from both sides
-2 sin^2 x =-1/2

2sin^2 x = 1/2

sin^2 x =1/4

sin = +/- 1/2

This occurs at pi/6, 5 pi/6, 7 pi/6, 11 pi/6