MathDB
// angle bisectors wanted, isosceles (2011 From Tasks to Tasks, p8 Ukr)

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May 2, 2021
geometryangle bisectorparallelisosceles

Problem Statement

On the median ADAD of the isosceles triangle ABCABC, point EE is marked. Point FF is the projection of point EE on the line BCBC, point MM lies on the segment EFEF, points NN and PP are projections of point MM on the lines ACAC and ABAB, respectively. Prove that the bisectors of the angles PMNPMN and PENPEN are parallel.