Упростите выражение:
(1+sin α-cos2α-sin3α)/(2sin² α+sin α-1)

(1+sin α-cos2α-sin3α)/(2sin² α+sin α-1)=(2sin²a-2sinacos2a)/(-cos2a+sina)==2sina(sina-cos2a)/(sina-cos2a)=2sina