The figure below shows a right triangle ABC (angle B = 90 degree)
with the incircle I tangent to BC at D. The excircle E corresponding to BC is
tangent to BC and tangent to the extensions of AB and AC at F, G, and H,
respectively. The extensions of GD and FH meet at J. Prove that the
triangle GJH is an isosceles right triangle.
See also: Typography and poster of problem 1408.