Question

几道三角函数题1.已知sinx=m,x∈(π/2,3π/2),求tanx2.已知y=f(x)定义域为（-1,0）,求y=

Answer 1

1.cosx=-sqrt(1-m^2) [余弦函数在二三象限取负]

tanx=sinx/cosx=-(m/sqrt(1-m^2)

2.x∈(2kπ-π,0),k∈Z

3.第四象限 sin2θ=2sinθcosθ0,故sinθ