sinx+cosx/sinx-cosx=2 求sin^2x+2sinxcosx-1的值
问题描述:
sinx+cosx/sinx-cosx=2 求sin^2x+2sinxcosx-1的值
答
sinx+cosx/sinx-cosx=2
化简得sinx=3cosx
sin²=9cos²x
解出sin²=9/10
sinxcosx=3/10
sin^2x+2sinxcosx-1=9/10-2*3/10-1=1/2