cos (π/12) × cos(5×π/12)的值
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cos(π/12)×cos(5×π/12)的值cos(π/12)×cos(5×π/12)的值cos(π/12)×cos(5×π/12)的值cos(15)*cos(5*15)=cos(45-30)*co
cos (π/12) × cos(5×π/12)的值
cos (π/12) × cos(5×π/12)的值
cos (π/12) × cos(5×π/12)的值
cos(15)*cos(5*15)
=cos(45-30)*cos(45+30)
=(cos45*cos30+sin45*sin30)(cos45cos30-sin45*sin30)
=(cos45cos30)^2-(sin45*sin30)^2
=(根号2/2*根号3/2)^2-（根号2/2*1/2）^2
=(1/2*3/4)-(1/2*1/4)
=3/8-1/8
=1/4
化简cos（π/12）*cos（5π/12）
cos (π/12) × cos(5×π/12)的值
cos(π/12)cos(5π/12)=
cos(α+5π/12)cos(α+π/6)+cos(π/12-α)cos(π/3-α) 化简
计算cos(a+5π/12)cos(a+π/6)+cos(π/12-a)cos(π/3-a）
cos(-π/12)过程
cosπ/12=
计算：cos（π/5)+cos（2π/5)+cos(3π/5)+cos(4π/5)
求值:cos(π/11)cos(2π/11)cos(3π/11)cos(4π/11)cos(5π/11)
求值：cos(π/11)-cos(2π/11)+cos(3π/11)-cos(4π/11)+cos(5π/11)
cos(π/11)cos(2π/11)cos(3π/11)cos(4π/11)cos(5π/11)
（sinπ/24)(cosπ/24)(cosπ/12)
（sinπ/24)(cosπ/24)(cosπ/12)
计算cos(π/5)cos(2π/5)的值
cos（5π/8）*cosπ/8
cos(5π/8)*cos（π/8)=
cosπ/12等于多少
化简cos^8(π/8)+cos^8(3π/8)+cos^8(5π/8)+cos^8(7π/8)