Question

cos(3pi-2a)/2sin^2(5pi/4+a)

Answer 1

$\frac{cos(3\pi -2a)}{2sin^2(\frac{5\pi }{4}+a)}=\frac{-cos2a}{2sin^2(\pi+\frac{\pi}{4}+a)}=\frac{cos2a}{2sin^2(\frac{\pi}{4}+a)}$