Question

tg (a-p)cos (p/2+2)cos (p+a)/sin (-a)ctg (3p/2+a)

Answer 1

$displaystyle frac{tg( alpha - pi )cos( frac{ pi }{2}+alpha)cos( pi +alpha) }{sin(-alpha)ctg( frac{3 pi }{2}+alpha) } = frac{tgalpha(-sinalpha)(-cosalpha)}{(-sin alpha)(-tgalpha)} =cosalpha$