化简:cosα+cos(2π/3-α)+cos(2π/3+α)

cos^2α+cos^2(α+π/3)-cosαcos(α+π/3)化简 化简:cosα+cos(2π/3-α)+cos(2π/3+α) 求和：cos(0)+cos(α)+cos(2α)+cos(3α)+……cos(nα) 2sinα*cosα*cos(2π-α)+cos(π+2α)*cosα*tanα化简! cos(α+5π/12)cos(α+π/6)+cos(π/12-α)cos(π/3-α) 化简 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 [sin(5π-α)cos(-π-α)]/[cos(α-π)cos(π/2+α)]化简 化简cos平方α+cos平方（α-π/3)+cos平方（α+π/3) 急、~ 【紧急求助】计算:cosα+cos(2π/3 +α)+cos（4π/3 +α） 化简sin(α-2π)+sin(-a-3π)cos(α-3π)/cos(π-α)-cos(-π-α)cos(α-4π) 化简:cos(-π-α) cos^3(-π-α) 求和：cosα+cos(2α)+cos(3α)+……+cos(nα) 化简cosαcosα/2cosα/2^2cosα/2^3……cosα/2^n-1 【2cos³α-cos²α+cosα-2】/2cos²α+cosα+2化简 化简2sin[(π/2)+α]-cos(-π+α)/cos(3π+aα)