SINα=2/3 则COS(π-2α)=?

3sinα=2cosα,则 cosα-sinα/cosα+sinα/ cos3sinα=2cosα,则cosα-sinα/cosα+sinα/cosα+sinα/cosα-sinα 已知3sinα=cosα,则sinα-2sinαcosα+3cosα+1= 已知sin(3π-α)=-2sin(π/2+α)则sinαcosα sinα+cosα/sinα-cosα =2 则2sin^2α-3sinαcosα-3cos^2α的值 设角a=-35π/6,则2sin(π+α)cos(π-α)-cos(π+α)/ 1+sin^2α+sin(π-α)-cos^2(π+α)sina=sin(-35π/6)=sin(-6π+π/6)=1/2 cosα=根号3/22sin(π＋α)cos(π-α)-cos(π+α)/ [1+sin^2α+sin(π-α)-cos^2(π+α)]=2（-sinα)(-cosα）+cosα/[1+sin² 已知sin(7π-α)-3cos(3π/2+α)=2,则(sin(π-α)+cos(π+α))/(sinα+cos(-α))的值是 已知sin(7π-α)-3cos(π-α)=2,则(sin(π-α)+cos(π+α))/(sinα+cos(-α))的值是 已知sin(7π-α)-3cos(π-α)=2,则(sin(π-α)+cos(π+α))/(sinα+cos(-α))的值是 tanα=3,则sin^2α-3sinαcosα+cos^α=? 2sinα-cosα=根号3 ×sinα,则cos α= 2sinα-cosα=根号3sinα,则cosα 若1+cosα/sinα=2 则cosα-3sinαRT... 若（sinα+cosα）/（sinα-cosα）=2 则sin(α-5π)·sin(3π/2-α)=? sinα=-2cosα,求sin^2α-3sinαcosα+1 若sinα+cosα/sinα-cosα=2,则sin(α-5π）*sin（3π/2-α）等于? sinα+cosβ=1/2,则sin^3α+cos^3β= 已知tanα=-3则7sinα-3cos/4sinα+5cosα=2sinαcosα-3cos^2α= 2sinα-3cosα/4sinα-9cosα=-1,则9sin^2α-3sinαcosα-5=