Question

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

Answer 1

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