三角函数的和差倍公式指的是：sin(A ± B)、cos(A ± B)、tan(A ± B)以及cot(A ± B)的公式。推导sin(A ± B) 的公式：根据正弦函数的定义，可以得到：sin(A ± B) = BC/AC = (AB sinC + AC sinB)/AC = sinA cosB ± cosA sinB推导cos(A ± B) 的公式：根据余弦函数的定义，可以得到：cos(A ± B) = AB/AC = (AB cosC - AC cosB)/AC = cosA cosB ∓ sinA sinB推导tan(A ± B) 的公式：tan(A ± B) = sin(A ± B)/cos(A ± B) = (sinA cosB ± cosA sinB)/(cosA cosB ∓ sinA sinB) = (tanA ± tanB)/(1 ∓ tanA tanB)推导cot(A ± B) 的公式：cot(A ± B) = cos(A ± B)/sin(A ± B) = (cosA cosB ∓ sinA sinB)/(sinA cosB ± cosA sinB) = (cotA cotB ∓ 1)/(1 ∓ cotA cotB)

cos(α+β)=cosαcosβ-sinαsinβ cos(α-β)=cosαcosβ+sinαsinβ sin(α+β)=sinαcosβ+cosαsinβ