Hi, everyone,

I have the trig function g(x)=cos^4(x)-cos^2(x) and i have found g'(x) to be -4sin(x)cos^3(x)+2sin(x)cos(x). how would i find when the derivative is equal to zero? I started to rearrange it to see if that would help but now i am stuck.

2sin(x)cos(x)=sin(2x) and,

-4sin(x)cos^3(x)=-4((1/2)sin(2x))cos^2(x)=-2sin(2x)cos^2(x).

Any ideas?

Thanks