求值cosπ/11*cos2π/11*cos3π/11*cos4π/11*cos5π/11求详细过程和重要步骤的原因(1/4*sin8π/11*cos3π/11*cos5π/11)/2sinπ/11=(1/4*sin3π/11*cos3π/11*cos5π/11)/2sinπ/11这一步骤是怎么变过来的
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![求值cosπ/11*cos2π/11*cos3π/11*cos4π/11*cos5π/11求详细过程和重要步骤的原因(1/4*sin8π/11*cos3π/11*cos5π/11)/2sinπ/11=(1/4*sin3π/11*cos3π/11*cos5π/11)/2sinπ/11这一步骤是怎么变过来的](/uploads/image/z/4036598-62-8.jpg?t=%E6%B1%82%E5%80%BCcos%CF%80%2F11%2Acos2%CF%80%2F11%2Acos3%CF%80%2F11%2Acos4%CF%80%2F11%2Acos5%CF%80%2F11%E6%B1%82%E8%AF%A6%E7%BB%86%E8%BF%87%E7%A8%8B%E5%92%8C%E9%87%8D%E8%A6%81%E6%AD%A5%E9%AA%A4%E7%9A%84%E5%8E%9F%E5%9B%A0%281%2F4%2Asin8%CF%80%2F11%2Acos3%CF%80%2F11%2Acos5%CF%80%2F11%29%2F2sin%CF%80%2F11%3D%281%2F4%2Asin3%CF%80%2F11%2Acos3%CF%80%2F11%2Acos5%CF%80%2F11%29%2F2sin%CF%80%2F11%E8%BF%99%E4%B8%80%E6%AD%A5%E9%AA%A4%E6%98%AF%E6%80%8E%E4%B9%88%E5%8F%98%E8%BF%87%E6%9D%A5%E7%9A%84)
求值cosπ/11*cos2π/11*cos3π/11*cos4π/11*cos5π/11求详细过程和重要步骤的原因(1/4*sin8π/11*cos3π/11*cos5π/11)/2sinπ/11=(1/4*sin3π/11*cos3π/11*cos5π/11)/2sinπ/11这一步骤是怎么变过来的
求值cosπ/11*cos2π/11*cos3π/11*cos4π/11*cos5π/11
求详细过程和重要步骤的原因(1/4*sin8π/11*cos3π/11*cos5π/11)/2sinπ/11
=(1/4*sin3π/11*cos3π/11*cos5π/11)/2sinπ/11这一步骤是怎么变过来的
求值cosπ/11*cos2π/11*cos3π/11*cos4π/11*cos5π/11求详细过程和重要步骤的原因(1/4*sin8π/11*cos3π/11*cos5π/11)/2sinπ/11=(1/4*sin3π/11*cos3π/11*cos5π/11)/2sinπ/11这一步骤是怎么变过来的
cosπ/11*cos2π/11*cos3π/11*cos4π/11*cos5π/11
=(cosπ/11*cos2π/11*cos3π/11*cos4π/11*cos5π/11*2sinπ/11)/2sinπ/11
=(sin2π/11*cos2π/11*cos3π/11*cos4π/11*cos5π/11)/2sinπ/11
=(1/2*sin4π/11*cos3π/11*cos4π/11*cos5π/11)/2sinπ/11
=(1/4*sin8π/11*cos3π/11*cos5π/11)/2sinπ/11
=(1/4*sin3π/11*cos3π/11*cos5π/11)/2sinπ/11
=(1/8*sin6π/11*cos5π/11)/2sinπ/11
=(1/8*sin5π/11*cos5π/11)/2sinπ/11
=(1/16*sin10π/11)/2sinπ/11
=1/32
解题关键在于利用与构造sin2x=2SinxCosx.如果不明白,等你追问.