Question

(cot^2)α((tan^2) α-(sin^2) α) 化简

Answer 1

(cotα)^2[(tan α)^2-(sinα)^2]

=1-(sinα)^2(cotα)^2

=1-(sinα)^2*(cosα)^2/(sinα)^2

=1-(cosα)^2

=(sinα)^2