f = Function(x^(3.0) - 3.0 * x + 1.0, 0.0, 1.0)
A = Intersect(f, d)

Tool: Orthocentre
Cliquer sur les trois sommets du triangle
Input: A, B, C
Output: D

a = Line(B, C)
b = Line(A, B)
c = OrthogonalLine(C, b)
d = OrthogonalLine(A, a)
D = Intersect(c, d)