angle wanted, isosceles, altitudes, rectangle (2018 Kyiv City MO 8.3)
Source:
September 11, 2020
geometryrectangleisoscelesangles
Problem Statement
In the isosceles triangle with the vertex at the point , the altitudes and are drawn. The point is such that is a rectangle. Find the value of the angle .(Bogdan Rublev)