(sinπ/24)(cosπ/24)(cosπ/12)

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(sinπ/24)(cosπ/24)(cosπ/12)(sinπ/24)(cosπ/24)(cosπ/12)(sinπ/24)(cosπ/24)(cosπ/12)由sin2α=2sinαcosα可得,

(sinπ/24)(cosπ/24)(cosπ/12)
(sinπ/24)(cosπ/24)(cosπ/12)

(sinπ/24)(cosπ/24)(cosπ/12)
由sin2α=2sinαcosα可得,(sinπ/24)(cosπ/24)=1/2*sinπ/12,
所以(sinπ/24)(cosπ/24)(cosπ/12) =1/2*(sinπ/12)*(cosπ/12)
=1/2*[1/2*sinπ/6]
=1/2*1/2*1/2
=1/8