c = AB 690 m
a = BC 710m
b = CA 920m
Berechnung mit Kosinussatz:
a^2 = b^2 +c^2 -2bc*cos(alpha);
alpha = arccos{ (a^2 -b^2 -c^2) / (-2bc) } ≈ 50°;
b^2 = a^2 +c^2 -2ac*cos(beta);
beta = arccos{ (b^2 -a^2 -c^2) / (-2ac) } ≈ 82°;
c^2 = a^2 +b^2 -2ab*cos(gamma);
gamma = arccos{ (c^2 -a^2 -b^2) / (-2ab) } ≈ 48°;
lg JR