求值:cosπ/17cos2π/17cos4π/17cos8π/17

来源:学生作业帮助网 编辑:作业帮 时间:2024/11/28 15:19:26
求值:cosπ/17cos2π/17cos4π/17cos8π/17
x){iÞ{f%o74F0 af$铦AΆ ;< 0O2B0MLrMzhC<$=DG5$bD & D,R ADHl @q

求值:cosπ/17cos2π/17cos4π/17cos8π/17
求值:cosπ/17cos2π/17cos4π/17cos8π/17

求值:cosπ/17cos2π/17cos4π/17cos8π/17
cos(π/17)cos(2π/17)cos(4π/17)cos(8π/17)
=[16sin(π/17)cos(π/17)cos(2π/17)cos(4π/17)cos(8π/17)]/16sin(π/17)
=[8sin(2π/17)cos(2π/17)cos(4π/17)cos(8π/17)]/16sin(π/17)
=[4sin(4π/17)cos(4π/17)cos(8π/17)]/16sin(π/17)
=[2sin(8π/17)cos(8π/17)]/16sin(π/17)
=sin(16π/17)/16sin(π/17)
=1/16