已知sinθ +0.5cosθ =0.5 求cosθ +0.5sinθ

问题描述:

已知sinθ +0.5cosθ =0.5 求cosθ +0.5sinθ

sinθ =0.5-0.5cosθ ,4-4cos²θ=1-2cosθ+cos²θ,cosθ=1或cosθ=-3/5,则sinθ=0或sinθ=4/5,所以cosθ +0.5sinθ =1或-0.2.