已知(1+tanθ)/(1-tanθ)=3+2√2,求1/2sin²θ-sinθcosθ

问题描述:

已知(1+tanθ)/(1-tanθ)=3+2√2,求1/2sin²θ-sinθcosθ

(1+tanθ)/(1-tanθ)=3+2√2tanθ=√2/2所以sinθ/cosθ=√2/2cosθ=√2sinθcos²θ=2sin²θ因为sin²θ+cos²θ=1所以sin²θ=1/5sinθcosθ=sinθ*√2sinθ=√2sin²θ=√2/5所以原式=(...