Доказать тождество. (sin²(3π/2+α))/ctg²(α-2π)+(sin²(-α))/ctg²(α-3/2 π) =1

Question

Доказать тождество.
(sin²(3π/2+α))/ctg²(α-2π)+(sin²(-α))/ctg²(α-3/2 π) =1

Answer 1

Cos^2 a/ctg^2 a +sin^2a/tg^2a=1;
sin^2a+cos^2a=1;
1=1