A = (1, -4, -2)
B = (4, 2, 7)
C = (5, -4, 10)
a = Plane(A, B, C)
Vieleck1, c, a_1, b = Polygon(A, B, C)
d = Line(A, B)
e = Line(A, C)
u: (1 / 3 * Vector[A, B])
v: (1 / 4 * Vector[A, C])