MathDB

In acute triangle

\triangle {ABC}

\angle A > \angle B > \angle C

\triangle {AC_1B}

and

\triangle {CB_1A}

are isosceles triangles such that

\triangle {AC_1B} \stackrel{+}{\sim} \triangle {CB_1A}

. Let lines

BB_1, CC_1

intersects at

{T}

. Prove that if all points mentioned above are distinct,

\angle ATC

isn't a right angle.

Problem Statement