证明sina减tana=sina乘tana

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证明sina减tana=sina乘tana
证明sina减tana=sina乘tana

证明sina减tana=sina乘tana
你好这个题的结论不对
应该是tan^2a-sin^2a=sin^2atan^2
证明
tan^2a-sin^2a
=sin^2a/cos^2a-sin^2a
=sin^2a(1/cos^2a-1)
=sin^2a(1/cos^2a-cos^2a/cos^2a)
=sin^2a((1-cos^2a)/cos^2a)
=sin^2a(sin^2a/cos^2a)
=sin^2atan^2