已知sinxcosx=3/8,且x∈(π/4,π/2),则cosx-sinx等于
网友回答
x∈(π/4,π/2)
cosx(cosx-sinx)²=cos²x+sin²x-2sinxcosx
=1-2*3/8
=1/4cosx-sinx=-√(1/4)=-1/2
======以下答案可供参考======
供参考答案1:
x∈(π/4,π/2)
cosxcosx-sinx=-√(cosx-sinx)^2
=-√(1-2sinxcosx)
=-√(1/4)
=-1/2供参考答案2:
sinxcosx=3/8
sin2x=3/4
(cosx-sinx)^2=1-sin2x=1/4
cosx-sinx=1/2