sin(2x+y)/sinx-2cos(x+y) 化简
化简sin(x+y)sinx+cos(x+y)cosx等于?
化简sin(x+y)sinx+cos(x+y)cosx
化简cos(x+y)sinx-sin(x+y)cosx
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]
化简sin(2x-y)*sin y+cos(2x-y)*sin y
请问怎么证明sinX+sin(X+Y)+sin(X+2Y)/cosX+cos(X+Y)+cos(X+2Y)=tan(X+
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]|
为什么sin(x+y) - sinx = 2cos(x+y/2)siny/2