已知siny=m*sin（2x+y)(m不等于一） 求证tan(x+y)=(1+m/1-m)*tanx
问题描述：
已知siny=m*sin（2x+y)(m不等于一） 求证tan(x+y)=(1+m/1-m)*tanx
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答
siny=m*sin(2x+y)
sin(x+y-x)=m*sin(x+y+x)
sin(x+y)cosx-cos(x+y)sinx=m[sin(x+y)cosx+cos(x+y)sinx]
(1-m)sin(x+y)cosx=(1+m)cos(x+y)sinx
sin(x+y)/cos(x+y)=(1+m)/(1-m)*sinx/cosx
tan(x+y)=(1+m)/(1-m)*tanx