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

Question

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

Answer 1

Cosx+cos²x=1/2-sin²x
cosx+cos²x+sin²x=1/2
cosx+1=1/2
cosx=-1/2
a)x=2pi/3+2k.pi
b)x=4pi/3+2k.pi
k=0,1,-1,2,-2,.......