Тригонометрия
- sin x=a/c
- cos x =b/c
- tg x =a/b=sin/cos x
- ctg x =b/a =cos x/sin x
- sin(π* -α)=sin α
- sin(π*/2-α)=cos α
- cos(π*/2-α)=sin α
- cos(α+2π*k)=sin α
- sin(α+2π*k)=cos α
- tg(α+2π*k)=tg
- ctg(α+2π*k)=ctg
- sin2 α+cos2 α=1
- ctg a=cos α/sin α, α≠π*n, n∈Z
- tg α*ctg α=1, α ≠(π*n)/2, n∈Z
- 1+tg α =1/cos2α, α ≠π*(2n+1)/2
- 1+ctg α =1/sin2α, α ≠π*n
*π ≈ 3,1415926535