MathDB

Let

I{}

be the incenter of triangle

ABC{}.

Let

N{}

be the foot of the bisector of angle

B{}.

The tangent line to the circumcircle of triangle

AIN

A{}

and the tangent line to the circumcircle of triangle

CIN{}

C{}

intersect at

D{}.

Prove that lines

AC{}

and

DI

are perpendicular.
Mikhail Evdokimov

Problem Statement