Concyclic Points Associated with an Angle Bisector and an Excircle

Initializing live version
Download to Desktop

Requires a Wolfram Notebook System

Interact on desktop, mobile and cloud with the free Wolfram Player or other Wolfram Language products.

Let ABC be a triangle with incenter I and circumcenter O, and let J be the excenter opposite A. Let the angle bisector from A intersect the circumcircle at M. Then B, C, I, and J lie on a circle centered at M.

Contributed by: Jay Warendorff (March 2011)
Open content licensed under CC BY-NC-SA



See problem 2.4(a) in V. Prasolov, Problems in Plane and Solid Geometry, Vol. 1, Plane Geometry [PDF], (D. Leites, ed. and trans.).

Feedback (field required)
Email (field required) Name
Occupation Organization
Note: Your message & contact information may be shared with the author of any specific Demonstration for which you give feedback.