Question

Помогите,пожалуйста! Срочно! cos²α-(1-2sin²α)

Answer 1

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Answer 2

$cos^2 alpha -(1-2sin^2 alpha )=(cos^2 alpha -1)+2sin^2 alpha =\\=-(1-cos^2 alpha )+2sin^2 alpha =-sin^2 alpha +2sin^2 alpha =sin^2 alpha$