Question 1178161
sin^2 x=1-cos^2 x
so 2-2cos^2x=1-cos x
0=2 cos^2 x-cos x -1
0=(2 cos x+1)(cos x-1)
cos x =-0.5
cos x=+1
x=0 degrees, 120 degrees, 240 degrees
{{{graph(300,300,-6,6,-1,2,2sin(x)^2+cos(x)-1)}}}