Can someone help with this pre-calc question

solve this equation for 0 sin^2 x+ cos 2x- cos x= 0

Hi,
You can use the fact that cos 2x=cos^2 x - sin^2 x:
sin^2 x+ cos 2x - cos x = 0
sin^2 x+ cos^2 x - sin^2 x - cos x = 0
cos^2 x - cos x = 0
cos(x)(cos(x) - 1) = 0
And a product is 0 when any of its factors is 0, so:
cos(x)=0 when x=90,270
cos(x)-1=0 ---> cos(x)=1 when x=0,360
Finally, the solution: sin^2 x+ cos 2x- cos x= 0 when x=0,90,270,360