已知tanθ/2 求 1-cosθ除以sinθ
问题描述：
已知tanθ/2 求 1-cosθ除以sinθ
答
(1-cosθ)/sinθ
=2sin²θ/2÷2sinθ/2cosθ/2
=sinθ/2÷cosθ/2
=tanθ/2
答
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)