cosπ/17cos2π/17cos4π/17cos8π/17
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cosπ/17cos2π/17cos4π/17cos8π/17cosπ/17cos2π/17cos4π/17cos8π/17cosπ/17cos2π/17cos4π/17cos8π/17cosπ/17
cosπ/17cos2π/17cos4π/17cos8π/17
cosπ/17cos2π/17cos4π/17cos8π/17
cosπ/17cos2π/17cos4π/17cos8π/17
cosπ/17cos2π/17cos4π/17cos8π/17
=sinπ/17*cosπ/17*cos2π/17*cos4π/17*cos8π/17 / sinπ/17
=1/2*sin2π/17*cos2π/17*cos4π/17*cos8π/17 / sinπ/17
=1/4sin4π/17*cos4π/17*cos8π/17 / sinπ/17
=1/8*sin8π/17*cos8π/17 / sinπ/17
=1/16*sin16π/17 / sinπ/17
sin16π/17=sinπ/17
所以原式=1/16
把这个式子乘以2sin(pi/17),之后再除以它,就解决啦
求值：cosπ/17cos2π/17cos4π/17cos8π/17
cosπ/17cos2π/17cos4π/17cos8π/17
cosπ/17cos2π/17cos4π/17cos8π/17=___
cosπ/9*cos2π/9*cos4π/9=?
cosπ/7cos2/7πcos4/7π=
化简cosπ/9*cos2π/9*cos3π/9*cos4π/9
求cosπ/9*cos2π/9*cos3π/9*cos4π/9
cosπ/5 +cos2π/5 +cos3π/5 +cos4π/5 =可以简写.
求cosπ/5乘cos2π/5乘cos3π/5乘cos4π/5
计算：cosπ/15×cos2π/15×cos4π/15×cos8π/15
求值cosπ/5cos2π/5cos4π/5cos8π/5
cosπ/7cos2π/7cos4π/7cos8π/7=?每步都写
cosπ/9cos2π/9cos3π/9cos4π/9=
化简cosπ/7*cos2π/7*cos4π/7 提示：据分析应该用倍角公式.
求cosπ/9*cos2π/9*cos4π/9的值如题
求值:cosπ/7·cos2π/7·cos4π/7
cosπ/9*cos2π/9*cos4π/9怎么算的?
急 、COSπ/9*COS2π/9*COS4π/9=?同样,