求证:sinx+siny=2sin(x+y)/2cos(x-y)/2
1个回答
展开全部
x=(x+y)/2+(x-y)/2
y=(x+y)/2-(x-y)/2
sinx+siny=sin[(x+y)/2+(x-y)/2]+sin[(x+y)/2-(x-y)/2]
=sin(x+y)/2cos(x-y)/2+cos(x+y)/2sin(x-y)/2+sin(x+y)/2cos(x-y)/2-cos(x+y)/2sin(x-y)/2
=2sin(x+y)/2cos(x-y)/2
y=(x+y)/2-(x-y)/2
sinx+siny=sin[(x+y)/2+(x-y)/2]+sin[(x+y)/2-(x-y)/2]
=sin(x+y)/2cos(x-y)/2+cos(x+y)/2sin(x-y)/2+sin(x+y)/2cos(x-y)/2-cos(x+y)/2sin(x-y)/2
=2sin(x+y)/2cos(x-y)/2
本回答被提问者采纳
已赞过
已踩过<
评论
收起
你对这个回答的评价是？
推荐律师服务：
若未解决您的问题，请您详细描述您的问题，通过百度律临进行免费专业咨询
