MathDB
midpoint of segment in a triangle 75-60-45

Source: BMO SL 2019, G2

November 8, 2020
geometry

Problem Statement

Let be a triangle ABC\triangle ABC with m(ABC)=75m(\angle ABC) = 75^{\circ} and m(ACB)=45m(\angle ACB) = 45^{\circ}. The angle bisector of CAB\angle CAB intersects CBCB at point DD. We consider the point E(AB)E \in (AB), such that DE=DCDE = DC. Let PP be the intersection of lines ADAD and CECE. Prove that PP is the midpoint of segment ADAD.