如何证明(tanb X sinb)/(tanb - sinb)与(tanb + sinb)/(tanb X sinb)相等

问题描述:

如何证明(tanb X sinb)/(tanb - sinb)与(tanb + sinb)/(tanb X sinb)相等

(tanb X sinb)/(tanb - sinb)=(tanb + sinb)/(tanb X sinb)
tan^2b*sin^2b=tan^2b-sin^2b
sin^4b=sin^2b-sin^2bcos^2b
=sin^2b(1-cos^2b)
=sin^4b
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