Question

Даю 90 баллов делайте

Answer 1

ctg(2π -α) = -ctg(α)

sin(α- π/2)= -cos(α)

ctg²(2π -α) - sin(α- π/2)* 1/cos(α) = (-ctg(α))² + cos(α) * 1/cos(α) =

= ctg²(α) + 1 =  1/sin²(α)