| maFigure A B C d1 d2 H|
maFigure := DrGeoCanvas new.
A := maFigure point: 3@3.
B := maFigure point: 6@0.
C := maFigure point: -3@0.
d1 := maFigure perpendicular: (maFigure segment: A to: B) at: C.
d2 := maFigure perpendicular: (maFigure segment: A to: C) at: B.
H := maFigure intersectionOf: d1 and: d2.