Question

(1+cos(Pi+B))/sin(Pi-B)

Answer 1

$frac{1+cos( pi + beta )}{sin( pi - beta )}=frac{1-cos(beta )}{sin( beta )}= frac{2sin ^{2} frac{ beta }{2} }{2sin frac{ beta }{2}cos frac{ beta }{2} } =tg frac{ beta }{2}$