(2-2/sin^2 (пи+альфа)(1/cos^2(альфа-пи)-1)

Question

(2-2/sin^2 (пи+альфа)(1/cos^2(альфа-пи)-1)

Answer 1

2((sin^2(a)-1)/sin^2(a))((1-cos^2(a))/cos^2(a))=2ctg^2(a)*tg^2(a)=2