求问一道高一数学计算题.cos(π/15)cos(2π/15)cos(4π/15)cos(8π/15)

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求问一道高一数学计算题.cos(π/15)cos(2π/15)cos(4π/15)cos(8π/15)
求问一道高一数学计算题.
cos(π/15)cos(2π/15)cos(4π/15)cos(8π/15)

求问一道高一数学计算题.cos(π/15)cos(2π/15)cos(4π/15)cos(8π/15)
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
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