sin^2x = 2 cos x + 2sin2x=2cosx+2
1 - cos^2 x = 2 cos x + 21−cos2x=2cosx+2
cos^2 x + 2 cos x + 2 - 1 = 0cos2x+2cosx+2−1=0
cos^2 x + 2 cos x + 1 = 0cos2x+2cosx+1=0
(cos x = 1)^2 = 0(cosx=1)2=0
cos x + 1 = 0cosx+1=0
cos x = -1 cosx=−1
color(purple)(x = cos ^-1 -1 = cos^-1 cos (pi) = pix=cos−1−1=cos−1cos(π)=π