solve for x: 4sin^2x= 4cosx+1

Answer 1

4sin^2 = 4cos + 1
4 - 4cos^2 = 4cos + 1
4cos^2 + 4cos - 3 = 0
(2cos-1)(2cos+3) = 0
so, cosx = 1/2 or -3/2

-3/2 is not a choice, so just find where cosx = 1/2.

Answer 2

answers: A. pi/3, 5pi/3

B. pi/3, 4pi/3

C. pi/3, 2pi/3

D. none