已知tanθ/2 求 1-cosθ除以sinθ

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已知tanθ/2 求 1-cosθ除以sinθ

已知tanθ/2 求 1-cosθ除以sinθ
已知tanθ/2 求 1-cosθ除以sinθ

已知tanθ/2 求 1-cosθ除以sinθ
两倍角公式:
cosθ=1-2sin²(θ/2)
sinθ=2sin(θ/2)cos(θ/2)
(1-cosθ)/sinθ
=2sin²(θ/2)/[2sin(θ/2)cos(θ/2)]
=sin(θ/2)/cos(θ/2)
=tan(θ/2)

(1-cosθ)/sinθ
=2sin²θ/2÷2sinθ/2cosθ/2
=sinθ/2÷cosθ/2
=tanθ/2