cos9分之派cos9分之2派cos9分之4派等于多少?
展开全部
原式=2sin(π/9)cos(π/9)cos(2π/9)cos(4π/9)/2sin(π/9)
=sin(2π/9)cos(2π/9)cos(4π/9)/2sin(π/9)
=2sin(2π/9)cos(2π/9)cos(4π/9)/4sin(π/9)
=sin(4π/9)cos(4π/9)/4sin(π/9)
=sin(8π/9)/8sin(π/9)
=sin(π-8π/9)/8sin(π/9)
=sin(π/9)/8sin(π/9)
=1/8
=sin(2π/9)cos(2π/9)cos(4π/9)/2sin(π/9)
=2sin(2π/9)cos(2π/9)cos(4π/9)/4sin(π/9)
=sin(4π/9)cos(4π/9)/4sin(π/9)
=sin(8π/9)/8sin(π/9)
=sin(π-8π/9)/8sin(π/9)
=sin(π/9)/8sin(π/9)
=1/8
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
