Объяснение:
Sin^2 α ∙ ctg^2 α : ( 1- sin^2 α )=
Sin^2 α ∙( cos^2 α )/sin^2 α ( 1- sin^2 α )=
= cos^2 α * (cos^2 α )=cos^4 α
Объяснение:
Sin^2 α ∙ ctg^2 α : ( 1- sin^2 α )=
Sin^2 α ∙( cos^2 α )/sin^2 α ( 1- sin^2 α )=
= cos^2 α * (cos^2 α )=cos^4 α