cos(π/15)cos(2π/15)cos(4π/15)cos(8π/15)
=sin(π/15)cos(π/15)cos(2π/15)cos(4π/15)cos(8π/15)/sin(π/15)
=1/2sin(2π/15)cos(4π/15)cos(8π/15)/sin(π/15)
=1/16sin(16π/15)/sin(π/15)
=1/16sin(π/15+π)/sin(π/15)
=-1/16
希望对你有所帮助! cos(π/15)cos(2π/15)cos(4π/15)cos(8π/15)
=sin(π/15)cos(π/15)cos(2π/15)cos(4π/15)cos(8π/15)/sin(π/15)
=1/2sin(2π/15)cos(4π/15)cos(8π/15)/sin(π/15)
=1/16sin(16π/15)/sin(π/15)
=1/16sin(π/15+π)/sin(π/15)
=-1/16
希望对你有所帮助!