三角函数积步喜获化和差，和差化积公式

三角函数积步喜获化和差，和差化积公式

和差化积

sinx+sin来明洲拿y=2sin[(x+y)/2]cos[(x-y)360问答/2]

sinx-siny=2cos[(x+y)/2]sin[(x-y)/2]

cosx+co为缺村类硫称建欢sy=2cos[(x+y)/2]cos[(x-y)/2]

cosx-cosy=-2sin[(x+y)/2]sin[(x-y)/2]

积化和差

sinxsiny=-1/2[cos(x+y)-cos(x-y)]

cosxcosy=1/2[cos(x+是合在派而y)+cos(x-y)]

sinxcosy=1/2[sin(x+y)+sin(x-y)]

cosxsiny=1/2[sin(x+y)-sin(x-y)]