Помогите номер 4 2)а,в

Question

Помогите номер 4 2)а,в

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Answer 1

А
(sina/cosa+cosa/sina)*(1-cos²a)=(sin²a+cos²a)/sinacosa * sin²a=sina/cosa=tga
b
(sin³acosa+cos^4a+sinacos³a-sin^4a)/sinacosa=
=[sinacosa(sin³a+cos³a)+(cos³a-sin³a)(cos³a+sin³a)]/sinacosa
=(sinacosa+cos2a)/sinacosa=1+2cos2a/sin2a=1+2ctg2a