[] , [] , [^] , []Making a triangle (2) / (1)-2(GC World : Various Problems ,Can you make it?)
I drew additional lines.
Let's move point P.
(1) How was DEF made?
(2) Can you make a equilateral triangle?
(3) Can you make a right triangle?
(4) Are there any cases in which it becomes a shape other than a triangle?

GC/Win


Forum of Geometric Constructor by Y.Iijima