证sin^2a x tana+cos^2a x cota+2sinacosa=1/sinacosa

问题描述:

证sin^2a x tana+cos^2a x cota+2sinacosa=1/sinacosa

sin^2a x tana+cos^2a x cota+2sinacosa
=sin³a/cosa+cos³a/sina+2sinacosa
=(sin^4a+cos^4a+2sin²acos²a)/sinacosa
=(sin²a+cos²a)²/sinacosa
=1/sinacosa
得证