神马作文网倍角公式与和角公式化简或求值cos π/17 * cos 2π/17 * cos 4π/17 * cos 8π/17
来源：学生作业帮 编辑：神马作文网作业帮 分类：数学作业 时间：2024/11/15 16:17:01
倍角公式与和角公式
化简或求值cos π/17 * cos 2π/17 * cos 4π/17 * cos 8π/17
化简或求值cos π/17 * cos 2π/17 * cos 4π/17 * cos 8π/17
分子分母同乘以16sin(π/17)即可利用二倍角公式化简
cos(π/17)cos(2π/17)cos(4π/17)cos(8π/17)
=[16sin(π/17)cos(π/17)cos(2π/17)cos(4π/17)cos(8π/17)]/16sin(π/17)
=[8sin(2π/17)cos(2π/17)cos(4π/17)cos(8π/17)]/16sin(π/17)
=[4sin(4π/17)cos(4π/17)cos(8π/17)]/16sin(π/17)
=[2sin(8π/17)cos(8π/17)]/16sin(π/17)
=sin(16π/17)/16sin(π/17)
=1/16
cos(π/17)cos(2π/17)cos(4π/17)cos(8π/17)
=[16sin(π/17)cos(π/17)cos(2π/17)cos(4π/17)cos(8π/17)]/16sin(π/17)
=[8sin(2π/17)cos(2π/17)cos(4π/17)cos(8π/17)]/16sin(π/17)
=[4sin(4π/17)cos(4π/17)cos(8π/17)]/16sin(π/17)
=[2sin(8π/17)cos(8π/17)]/16sin(π/17)
=sin(16π/17)/16sin(π/17)
=1/16
化简求值sin(-20/3π)cos(43/6π)+sin(35/6π)cos-(17/3π)
二倍角公式题求值：1/2-cos²π/8
8sin(π/32)cos(π/32)cos(π/16)cos(π/8),求值
求值cos5π/8*cosπ8
求值：cos（25π /4）
cos(π/32)*cos(π/16)*cos(π/8)=
利用二倍角公式求值sin(π/12)cos(π/12)
cos（－17/3π）＝?
求值：sin(π/12)+cos(π/12)
求SINπ/64 COSπ/64 COSπ/32 COSπ/16 COSπ/8
已知cos（π4
【紧急求助】计算:cosα+cos(2π/3 +α)+cos（4π/3 +α）