sinθ-cosθ=1/5,θ∈(o,π),求sin2θ
问题描述:
sinθ-cosθ=1/5,θ∈(o,π),求sin2θ
答
sinθ-cosθ=1/5
(sinθ-cosθ)^2=1-2sinθcosθ=1-sin2θ=1/25
sin2θ=24/25