作业帮cos2/15π+cos4/15π+cos8/15π+cos16/15π
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cos2/15π+cos4/15π+cos8/15π+cos16/15π
cos2/15π+cos4/15π+cos8/15π+cos16/15π
cos2/15π+cos4/15π+cos8/15π+cos16/15π
cos(2π/15)+cos(4π/15)+cos(8π/15)+cos(16π/15)
=2cos(9π/15)cos(7π/15)+2cos(6π/15)cos(6π/15)cos(2π/15)
=2cos(3π/5)*[cos(7π/15)-cos(2π/15)]
=-4cos(3π/5)sin(3π/10)sin(π/6)
=-2cos(3π/5)sin(3π/10)
cos2/15π+cos4/15π+cos8/15π+cos16/15π
计算：cosπ/15×cos2π/15×cos4π/15×cos8π/15
cos2/7π*cos4/7π*cos6/7π=?
求值：cos2π/7 * cos4π/7 * cos6π/7
cosπ/9*cos2π/9*cos4π/9=?
求值cos2π/9*cos4π/9*8π/9
cosπ/7cos2/7πcos4/7π=
求值:cos2π/7cos4π/7cos8π/7
cos2π/7+cos4π/7+6π/7=
cos2π/7cos4π/7cos6π/7=?
cos2π/7+cos4π/7+cos6π/7=
求值cos2π/9cos4π/9cos8π/9
cos2/7π+cos4/7π+cos6/7=
cosπ/15 cos2π/15 cos3π/15 cos4π/15 cos5π/15 cos6π/15 cos7π/15他们都相乘 求等于多少
化简cosπ/9*cos2π/9*cos3π/9*cos4π/9
求cosπ/9*cos2π/9*cos3π/9*cos4π/9
化简sin π/7(cos2π/7+cos4π/7+cos6π/7)
cos1/5π+cos2/5π+cos3/5π+cos4/5π=多少