求证:cosαcos(π/3+α)cos(π/3-α)=cos3α如题,求证:4cosαcos(π/3+α)cos(π/3-α)=cos3α不好意思 少打个4

求证：|cosα+cosβ| 求证:cosαcos(π/3+α)cos(π/3-α)=cos3α如题,求证:4cosαcos(π/3+α)cos(π/3-α)=cos3α不好意思 少打个4 cos^3(-π-α) cos^2α+cos^2(α+π/3)-cosαcos(α+π/3)化简 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. 求和：cos(0)+cos(α)+cos(2α)+cos(3α)+……cos(nα) 求证cosα^2+cos(α+β)^2-2cosαcosβcos(α+β)=sinβ^2 求证cos(3π/2+α)=sinα cos(3π/2-α)=sinα求证 cosα cos(3π-α)=? 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) 【紧急求助】计算:cosα+cos(2π/3 +α)+cos（4π/3 +α） 求证：[tan（2π-α）cos（3π/2-α)cos(6π-α)]/[sin(α+3π/2)cos(α+3π/2)]=-tanα 化简:cos(-π-α) 求证cos（α+β）cos（α-β）=cos²α-sin²β