Помогите плз, нужен ответ!

Question

Помогите плз, нужен ответ!

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Answer 1

Sin(π/4-α).sin(π/4+α)-cos(π/4+α).cos(π/4-α)=-cos(π/4-α+π/4+α)=
=-cosπ/2=0
Otvet:c)0

(cos(α+β)=cosαcosβ-sinαsinβ, -cos(α+β)=sinαsinβ-cosαcosβ))