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) 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) cos（π/11）cos（2π/11）cos（3π/11）cos（4π/11）cos（5π/11）怎么解 求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)(5/24)(11/24)=5/11?,而且过程和题好像都没关系。 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( cos(-A-11π/2) =cos(A+11π/2)怎样计算来的? 计算：cos（π/5)+cos（2π/5)+cos(3π/5)+cos(4π/5) cos(π/17)*cos(2π/17)*cos(4π/17)*cos(8π/17) cos^2α+cos^2(α+π/3)-cosαcos(α+π/3)化简 ① 利用公式C（a－β)证明,cos(2π-a)=cos a 化简:[sin(2π-a)cos(π+a)cos(π/2+a)cos(11π/2-a)[sin(2π-a)cos(π+a)cos(π/2+a)cos(11π/2-a)]/[cos(π-a）sin(3π-a)sin(-π-a)sin(9π/2+a)] 化简:sin(2π-α)cos(π+α)cos(11π/2-α)/cos(π-α)sin(3π-α)sin(-π-α)sin(9π/2+α) 已知三角型abc三内角a b c 成等差数列,且a-c=π/3,求cos^2a+cos^2b+cos^c的值 三角函数计算cosα=1／7,cos（α+β）=-11／14,α、β∈（0,π／2）,求cosβ 已知COSα=1/7,COS（α+β）=-11/14,且α,β属于0到2/π,求COSβ 已知cosα=1/7,cos（α+β）=-11/14,且α、β∈（0,2/Π）,求cosβ的值 cos(180/11)cos(360/11)cos(540/11)cos(720/11)cos(900/11)