Доказать тождество(sin 2a+cos a)/(cos^2 a+sin^2 a+2sin a)=cos a

Question

Доказать тождество
(sin 2a+cos a)/(cos^2 a+sin^2 a+2sin a)=cos a

Answer 1

(2cos a sin a+cos a)/(1+2sin a)=cos a (2sin a+1)/(1+2sin a)=cos a

Answer 2

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