You can put this solution on YOUR website!
Hi, think of this as regular factoring steps.
step 1 - factor out a cos(x) to get
step 2 -set each part = 0 and solve for x. We get
cos(x) = 0
x = pi/2, or 3pi/2
3cos(x) -2 = 0
cos(x) = 2/3
we estimate this as 48.1 degrees
so we have 48.1, 90, and 270 degrees
since this is not an identity, we can't "prove" for all x.