2sin(x+y)*siny+cos(x+2y)可以化简为什么?
为什么sin(x+y) - sinx = 2cos(x+y/2)siny/2
sin x *cos y-cos x*siny 用Mathematica怎么化简
请问,如何证明sinx+siny=2*sin(x+y/2)*cos(x-y/2)
求证sinx+siny=2sin(x+y)/2*cos(x-y)/2
求证|sinx-siny|=|2sin[(x-y)/2]cos[(x+y)/2]|
证明 [sin(2x+y)/sinx]-2cos(x+y)=siny/sinx
求证:sin(2x+y)/sinx-2cos(x+y)=siny/sinx
求证:sin(x-y)/(sinx-siny)=cos[(x-y)/2]/cos[(x+y)/2]
已知x-y=派/3,且sin x-siny=1/2,求cos(x+y).
两角和差公式sinx-siny=2sin[(x-y)/2]cos[(x+y)/2]推导.
证明sinx+siny+sinz-sin(x+y+z)=4sin((x+y)/2)sin((x+y)/2)sin((x+
证明sin(x+y)sin(x-y)=(sinx)^2-(siny)^2.