MathDB

JBMO Shortlist 2019 G1

Source:

September 12, 2020

geometry

Problem Statement

Let

ABC

be a right-angled triangle with

\angle A = 90^{\circ}

and

E

. The perpendicular at the midpoint

M

of

BC

meets the bisector

BK

of the angle

B

at the point

E

. The perpendicular bisector of

EK

meets

AB

at

D

. Prove that

KD

is perpendicular to

DE

.
Proposed by Greece

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