\text{Stačí dokázať, že }

D - S = S - A \ \
E - S = S - B \ \
F - S = S - C

\text{Dôkaz urobíme pre prvú rovnosť:

D - S = A + 2u + 2v - (A + u + v) =

A = (-0.08, -0.04)
U_{1} = (0.5, -1.04)
U_{2} = (2.74, -0.2)
u = Vector(U_{1}, U_{2})
V_{1} = (4.38, 3.32)
V_{2} = (2.7, 5.82)
v = Vector(V_{1}, V_{2})