MathDB
<ACB=60 iffAE + BD = AB, angle bisectors (2016 Kyiv City MO 8.5)

Source:

September 5, 2020
geometryangle bisectorangles

Problem Statement

In the triangle ABCABC the angle bisectors ADAD and BEBE are drawn. Prove that ACB=60\angle ACB = 60 {} ^ \circ if and only if AE+BD=ABAE + BD = AB.
(Hilko Danilo)