Tétel
s(x+y)=sin(x)*cos(y)+cos(x)*sin(y)
Bizonytás
sin(x+y)=cos(π/2-(x+y))=cos((π/2-x)-y)=cos(π/2-x)*cos(y)+sin(π/2-x)*sin(y)=sin(x)*cos(y)+cos(x)*sin(y)
Tétel
s(x+y)=sin(x)*cos(y)+cos(x)*sin(y)
Bizonytás
sin(x+y)=cos(π/2-(x+y))=cos((π/2-x)-y)=cos(π/2-x)*cos(y)+sin(π/2-x)*sin(y)=sin(x)*cos(y)+cos(x)*sin(y)