化简（-11/6 π)+cos(12/5 π)tan（4π）-1/(cos(13π/3))

cos(α+5π/12)cos(α+π/6)+cos(π/12-α)cos(π/3-α) 化简 化简cos（π/12）*cos（5π/12） 化简（-11/6 π)+cos(12/5 π)tan（4π）-1/(cos(13π/3)) 计算cos(a+5π/12)cos(a+π/6)+cos(π/12-a)cos(π/3-a） 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) 化简sin（25π/12）cos（11π/6）-cos（11π/12）sin（5π/6）的值是 利用诱导公式求三角函数值 cos 6/65π一,利用诱导公式:cos（2kπ+α）=cosα （k∈Z）和cos（π－α）=－cosα 得出cos65π/6=cos(65π/6-10π)=cos(5π/6)=cos(π-π/6)=-cosπ/6=-√3/2二,又或者cos65π/6=cos(11π-1π/6)=-cos( 化简cos(π/12-α)-根号3cos(5π/12+α) 化简cos(π/6+x)+cos(π/6-x) 化简cos(π/6a)+cos(π／6-a)= cos (π/12) × cos(5×π/12)的值 cos(π/12)cos(5π/12)= 化简cos^8(π/8)+cos^8(3π/8)+cos^8(5π/8)+cos^8(7π/8) [sin(5π-α)cos(-π-α)]/[cos(α-π)cos(π/2+α)]化简 cos（π/11）cos（2π/11）cos（3π/11）cos（4π/11）cos（5π/11）怎么解 Cos[π/7] + Cos[2 π/7] + Cos[3 π/7] + Cos[4 π/7] + Cos[5 π/7] + Cos[6 π/7] + Cos[7π/7]过程思路 不要只有答案哦