化简:(1/tan(a/2)-tana/2)(1+tanatana/2)

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化简:(1/tan(a/2)-tana/2)(1+tanatana/2)
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化简:(1/tan(a/2)-tana/2)(1+tanatana/2)
化简:(1/tan(a/2)-tana/2)(1+tanatana/2)

化简:(1/tan(a/2)-tana/2)(1+tanatana/2)
设a=A则
(1/tanA/2-tanA/2)(1+tanAtanA/2)
=[(1-tan²A/2)/tanA/2][1+2tan²A/2/(1-tan²A/2)]
=[(1-tan²A/2)/tanA/2][(1+tan²A/2)/(1-tan²A/2)]
=(1+tan²A/2)/tanA/2
=sec²A/2/tanA/2
=2/sinA

(1/tanA/2-tanA/2)(1+tanAtanA/2)
=[(1-tan²A/2)/tanA/2][1+2tan²A/2/(1-tan²A/2)]
=[(1-tan²A/2)/tanA/2][(1+tan²A/2)/(1-tan²A/2)]
=(1+tan²A/2)/tanA/2
=sec²A/2/tanA/2
=2/sinA
=2cscA