function [a,b,c,A,B,C] = cosinelaw(x,y)
%x=[xA,xB,xC], y=[yA,yB,yC]

%compute edge lengths
a = sqrt((x(3)-x(2))^2+(y(3)-y(2))^2);
b = sqrt((x(3)-x(1))^2+(y(3)-y(1))^2);
c = sqrt((x(2)-x(1))^2+(y(2)-y(1))^2);

%compute angles between incident edges per vertice
A = acos((-a^2+b^2+c^2)/(2*b*c));
B = acos((a^2-b^2+c^2)/(2*a*c));
C = acos((a^2+b^2-c^2)/(2*a*b));