求值cos2π/9cos4π/9cos8π/9

求值cos2π/9cos4π/9cos8π/9 求值:cos2π/7cos4π/7cos8π/7 求值：cosπ/17cos2π/17cos4π/17cos8π/17 求值cosπ/5cos2π/5cos4π/5cos8π/5 求值cos2π/9*cos4π/9*8π/9 cos2派/9×cos4派/9×cos8派/9等于 cos2/15π+cos4/15π+cos8/15π+cos16/15π 计算：cosπ/15×cos2π/15×cos4π/15×cos8π/15 cosπ/17cos2π/17cos4π/17cos8π/17 cosπ/17cos2π/17cos4π/17cos8π/17=___ cosπ/7cos2π/7cos4π/7cos8π/7=?每步都写 cos2π/7cos4π/7cos8π/7要过程 求值：cos2π/7 * cos4π/7 * cos6π/7 求值：cos2∏/7*cos4∏/7*cos8∏/7请尽快作答, 求值 cosπ/9cos2π/9cos4π/9还有一题：2·（根号下1+sin4）-（根号下2-2cos4） cosπ/9*cos2π/9*cos4π/9=? cosπ/11*cos2π/11*cos3π/11*cos4π/11*cos5π/11上式为何等于cosπ/11*cos2π/11*cos4π/11*cos8π/11*cos16π/11 求值：Cos2/7π＋Cos4/7π＋Cos6/7π