A: (2, -1, 0)
B: (3, -1, 2)
C: (0, 4, 1)
t1, c, b, a = Polygon(B, A, C)
α = Angle(B, A, C)
n: (2, 1, -1)
eq1: (2 * x) + y - z - 3 = 0
S: (0, 1, 4)
f = OrthogonalLine(S, eq1)
H = Intersect(f, eq1)