cos^2α+cos^2(α+π/3)-cosαcos(α+π/3)化简

cos^2α+cos^2(α+π/3)-cosαcos(α+π/3)化简 求和：cos(0)+cos(α)+cos(2α)+cos(3α)+……cos(nα) 求和：cosα+cos(2α)+cos(3α)+……+cos(nα) 化简:cosα+cos(2π/3-α)+cos(2π/3+α) 【紧急求助】计算:cosα+cos(2π/3 +α)+cos（4π/3 +α） 3sinα=2cosα,则 cosα-sinα/cosα+sinα/ cos3sinα=2cosα,则cosα-sinα/cosα+sinα/cosα+sinα/cosα-sinα Cos(α-π) Cos(α- π/2 )如何化简 cos(α+β)cos(α-β)=1/3,则cos^2α+cos^2β=?cos(α+β)cos(α-β)=1/3,则cos^2α+cos^2β=? cos(α+β)cos(α-β)=1/3,则cos^2α+cos^2β=?cos(α+β)cos(α-β)=1/3,则cos^2α+cos^2β=? sin(3π+α )=1/4,求cos(π+α)/cosα[cos(π+α)-1]+cos(α-2π)/cos(α+2π)cos(π+α)+coa(-α) 2sinα*cosα*cos(2π-α)+cos(π+2α)*cosα*tanα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 不等式证明1已知α、β、γ∈(0,π/2),且tanα+tanβ+tanγ＝3,求证：1/(cosαcosβ)+1/（cosβcosγ)+1/(cosγcosα)≥6. [sin(5π-α)cos(-π-α)]/[cos(α-π)cos(π/2+α)]化简 若sinα+cosβ=2/3 cosα+cosβ=5/6求cos(α-β) 化简sin(α-2π)+sin(-a-3π)cos(α-3π)/cos(π-α)-cos(-π-α)cos(α-4π)