Jawabanmu

2014-04-11T06:37:18+07:00
Bring stuff on the other side of the equation: 

cos^2 x = 1 - sin^2 x 
2cos^2 x - sin x - 1 = 0 
2(1 - sin^2 x) - sin x - 1 = 0 
2sin^2 x + sin x - 1 = 0 

Factor this 
(2 sin x - 1)(sin x +1) = 0 
2 sin x - 1 = 0 or sin x +1 = 0 
sin x = 1, and sin x = -1 

Answers: 
pi/6, and 3pi/2, adding 2pi times a constant, for each trip around the unit circle.
(Sin x-1) (2 cos x+1)

tidak sama dengan
SIN(x) -1 dst dst