已知θ为△ABC内角,且sinθ+cosθ=m,若0
问题描述:
已知θ为△ABC内角,且sinθ+cosθ=m,若0
答
(sinθ+cosθ)^2=(sinθ)^2+(cosθ)^2+2sinθcosθ=1+2sinθcosθ=m^2
已知θ为△ABC内角,且sinθ+cosθ=m,若0
(sinθ+cosθ)^2=(sinθ)^2+(cosθ)^2+2sinθcosθ=1+2sinθcosθ=m^2