来自刘雪莲的问题
【若tanθ=1/3,则cos²θ+1/2sin2θ的值】
若tanθ=1/3,则cos²θ+1/2sin2θ的值
1回答
2020-06-2415:37
【若tanθ=1/3,则cos²θ+1/2sin2θ的值】
若tanθ=1/3,则cos²θ+1/2sin2θ的值
答:
tanθ=1/3
cos²θ+(1/2)sin2θ
=(cos²θ+sinθcosθ)/(sin²θ+cos²θ)分子分母同除以cos²θ
=(1+tanθ)/(tan²θ+1)
=(1+1/3)/(1/9+1)
=(4/3)/(10/9)
=6/5