化简cos(α－3π)

cos^2α+cos^2(α+π/3)-cosαcos(α+π/3)化简 化简cos(α－3π) cos(α+5π/12)cos(α+π/6)+cos(π/12-α)cos(π/3-α) 化简 化简cos平方α+cos平方（α-π/3)+cos平方（α+π/3) 急、~ 化简:cosα+cos(2π/3-α)+cos(2π/3+α) 化简:cos(-π-α) cos^3(-π-α) 化简sin(π/2+α)cos(3π-α)tan(π+α)/cos(π/2-α)cos(-α-π) 化简{sin(π+α)^3cos(-α)cos(π+α)}/{tan(π+α)^3cos(-π-α)^2} (1+sinα+cosα)*[sin(α/2)-cos(α/2)]/√(2+2cosα)化简 （3/2*π 化简sin(α-2π)+sin(-a-3π)cos(α-3π)/cos(π-α)-cos(-π-α)cos(α-4π) 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2sin[(π/2)+α]-cos(-π+α)/cos(3π+aα) 化简cos(α- 5π/3)+cos(α+13π/3) 化简：sinα-√3 cosα+2cos(α-π/3) 化简cos(π/12-α)-根号3cos(5π/12+α) 三角函数化简cos(α)+cos(π/3+α)= 化简. 化简cos(1-π)+cos(3π+1)=