sinx=2cosx 则sin^2x=

证明:sin2x=2sinx*cosx为什么sin(x+x)=sinx*cosx+cosx*sinx? 求证 sin^2x/(sinx-cosx)-(sinx+cosx)/tan^2 x-1=sinx+cosx sinx+cosx/sinx-cosx=2 求sinx/cos^3x +cosx/sin^3x 求证sin^2x/sinx-cosx-(sinx+cosx)/(tan^2-1)=sinx+cosx谢谢GGJJ (sinx+3cosx)/(3cosx-sinx)=5,则sin^2x-sinxcosx的值是 sinx=2cosx 则sin^2x= sinx;sin(x/2)=8;5,则cosx=?sinx:sin(x/2)=8:5,则cosx=? sinx+cosx/sinx-cosx=2,则sin(x-5π)sin(3π/2-x)=? 利用cosx=sin(π/2-x),sin'x=cosx,证明(cosx)'=-sinx 已知sinx=2/3,求(cosx-sinx/cosx+sin)+(cosx+sin/cosx-sinx)的值. 3sinx-2cosx=0 (1)(cosx-sinx)/(cosx+sinx)+(cosx+sinx)/(cosx-sinx) (2)sin^2 x-2sinxcosx+4cos^2 x 证明(1+secx+tanx)/(1+secx-tanx)=(1+sinx)/cosx左边=（cosx/cosx+1/cosx+sinx/cosx)/（cosx/cosx+1/cosx-sinx/cosx)=(cosx+1+sinx)/(cosx+1-sinx)=(cosx+1+sinx)^2/[(cosx+1+sinx)(cosx+1-sinx)]=(cos²x+sin²x+2*sinx*cosx+2*cosx+2*sinx+1)/(cos² 已知sinx+cosx/sinx-cosx=3,求tanx,2sin^2x+(sinx-cosx)^2的值 已知(sinx+cosx)/(sinx-cosx)=3,求tanx,2sin²x+(sinx-cosx)²的值 已知(sinx+cosx)/(cosx-sinx)=2,则2sin²x-sinxcosx+cos²x=（ ）,求详解, 若(sin^2x+4)/cosx+1=2 则（cosx+3）(sinx+1)= 若tanX=2,则3sinX-4cosX/4sin X-cosX=? 已知(sinx-cosx)/(sinx+cosx)=2,则则sin^2x+2sinxcosx