MathDB
angle wanted, angle bisectors given (2021 Novosibirsk Oral Geo Oly 8.4)

Source:

May 24, 2021
geometryangle bisectorangles

Problem Statement

Angle bisectors ADAD and BEBE are drawn in triangle ABCABC. It turned out that DEDE is the bisector of triangle ADCADC. Find the angle BACBAC.