cosπ/9cos2π/9cos23π/9

cosπ/9cos2π/9cos23π/9 cosπ/9*cos2π/9*cos4π/9=? 求COSπ/5*COS2π/5 cosπ/5×cos2π/5= COSπ/5乘以COS2π/5 cosπ/5×cos2π/5 cosπ/5cos2π/5 cosπ/5cos2π/5=? 化简cosπ/9*cos2π/9*cos3π/9*cos4π/9 求cosπ/9*cos2π/9*cos3π/9*cos4π/9 cosπ/9cos2π/9cos3π/9cos4π/9= 求cosπ/9*cos2π/9*cos4π/9的值如题 cosπ/9*cos2π/9*cos4π/9怎么算的? 急 、COSπ/9*COS2π/9*COS4π/9=?同样, cosπ/5 - cos2π/5 怎样变成 cosπ/5 + cos2π/5rt 化简cos2α+cos2(π/3+α)+cos2(π/3-α)化简cos²α+cos²（π/3+α）+cos²（π/3-α） sinπ.cosπ.sin2π.cos2π分别是多少 求值:cosπ/7*cos2π/7*cos3π/7