sin(x+y)-sinx=2siny/2·cos(x+y/2)怎么来的

mmEmily2022-10-04 11:39:541条回答

已提交，审核后显示！提交回复

共1条回复

我的魅影共回答了15个问题 | 采纳率100%: sin(x+y)-sinx
=sin[(x+y/2)+y/2]-sin[(x+y/2)-y/2]
=sin(x+y/2)cos(y/2)+sin(y/2)cos(x+y/2) -[sin(x+y/2)cos(y/2)-cos(x+y/2)sin(y/2)]
=2siny/2·cos(x+y/2); 1年前

相关推荐

大家在问