[4 sin^2 (2x) cos^2 (x)] /[1 + 4 cos^2 (x) + 4 cos(2x) cos x] = sin^2 (x/8)
更新1:
Correction : Prove that the identity is true for x = 80 degree.
更新2:
To : 001. Do you think the identity is true for all other values of x? Or for a limited range of x ? Or for x = 80 only?
