请问,如何证明sinx+siny=2*sin(x+y/2)*cos(x-y/2)_其他解答

请问,如何证明sinx+siny=2*sin(x+y/2)*cos(x-y/2)

人气：323 ℃　时间：2020-05-03 02:29:40

解答

设A=(X+Y)/2,B=(X-Y)/2
X=A+B,Y=A-B
SINX=SIN(A+B)=SINACOSB+COSASINB
SINY=SIN(A-B)=SINACOSB-COSASINB
SINX+SINY=2SINACOSB