请问sinx=sin(x-120); 120
请问sin²x=sinx²吗
请问,如何证明sinx+siny=2*sin(x+y/2)*cos(x-y/2)
(sinX+sinθ) .(Sinx-sinθ)=sin(x+θ).cos(x-θ)证明
证明sin(x+y)sin(x-y)=sinx-siny
请问怎么证明cosnx*sinx+sinnx*cosx=sin(n+1)*x?
为什么(sin²x)' = 2sinx(sinx)'
sin²x+sinx=1则sinx等于多少?
2sinx=sin(60-x),求sinx的值
请问怎么证明sinX+sin(X+Y)+sin(X+2Y)/cosX+cos(X+Y)+cos(X+2Y)=tan(X+
sinx+cosx/sinx-cosx=2 求sinx/cos^3x +cosx/sin^3x
求证 sin^2x/(sinx-cosx)-(sinx+cosx)/tan^2 x-1=sinx+cosx
2sin(x/2)cos(x/2)=sinx请问这是个公式吗?还是推导出来的呢?