Geometry Problem, Online Education

Online Geometry Problem 601: Cyclic Quadrilateral, Incenter, Excenter, Angle Bisector, Rectangle

The figure shows a cyclic quadrilateral ABCD. If E is the incenter of triangle ABC, F the incenter of triangle BCD, G the excenter of triangle ABC, and H the excenter of triangle BCD, prove that EFGH is a rectangle.


Triangle, Cyclic quadrilateral, Incenter, Excenter, Rectangle