=无取值范围数关系tanα ·cotα=1sinα ·cscα=1cosα ·secα=1商的关系tanα=sinα/cosα cotα=cosα/sinα平方关系以下关系,函数名不变,符号看象限.sin(2kπ+α)=sinαcos(2kπ+α)=cosαtan(2kπ+α)=tanαcot(2kπ+α)=cotαsin(π+α)=-sinαcos(π+α)=-cosαtan(π+α)=tanαcot(π+α)=cotαsin(π-α)=sinαcos(π-α)=-cosαtan(π-α)=-tanαcot(π-α)=-cotαsin(2π-α)=-sinαcos(2π-α)=cosαtan(2π-α)=-tanαcot(2π-α)=-cotα以下关系,奇变偶不变,符号看象限sin(90°-α)=cosαcos(90°-α)=sinαtan(90°-α)=cotαcot(90°-α)=tanαsin(90°+α)=cosαcos(90°+α)=-sinαtan(90°+α)=-cotαcot(90°+α)=-tanαsin(270°-α)=-cosαcos(270°-α)=-sinαtan(270°-α)=cotαcot(270°-α)=tanαsin(270°+α)=-cosαcos(270°+α)=sinαtan(270°+α)=-cotαcot(270°+α)=-tanα积化和差公式sinα ·cosβ=(1/2)*[sin(α+β)+sin(α-β)]cosα ·sinβ=(1/2)*[sin(α+β)-sin(α-β)]cosα ·cosβ=(1/2)*[cos(α+β)+cos(α-β)]sinα ·sinβ=-(1/2)*[cos(α+β)-cos(α-β)]和差化积公式sinα+sinβ=2sin[(α+β)/2]·cos[(α-β)/2]sinα-sinβ=2cos[(α+β)/2]·sin[(α-β)/2]cosα+cosβ=2cos[(α+β)/2]·cos[(α-β)/2]cosα-cosβ=-2sin[(α+β)/2]·sin[(α-β)/2]三倍角公式sin3α=3sinα-4sin^3α;cos3α=4cos^3α-3cosα两角和与差的三角函数关系sin(α+β)=sinαcosβ+cosαsinβsin(α-β)=sinαcosβ