MathDB

Circumcenter equidistant from two points

Source: Sharygin Geometry Olympiad Correspondence Round 2017 P-10 (Grade-8-10)

May 1, 2017

geometrycircumcircle

Problem Statement

Points

K

and

L

on the sides

AB

and

BC

of parallelogram

ABCD

are such that

\angle AKD = \angle CLD

. Prove that the circumcenter of triangle

BKL

is equidistant from

A

and

C

. Proposed by I.I.Bogdanov