MathDB
computational, isosceles inscribed in semicircle, equilaterals

Source: OLCOMA Costa Rica National Olympiad, Final Round, 2014 3.4

October 1, 2021
semicircleequilateralsisoscelesgeometry

Problem Statement

Consider the isosceles triangle ABCABC inscribed in the semicircle of radius r r. If the BCD\vartriangle BCD and CAE\vartriangle CAE are equilateral, determine the altitude of DEC\vartriangle DEC on the side DEDE in terms of r r. https://cdn.artofproblemsolving.com/attachments/6/3/772ff9a1fd91e9fa7a7e45ef788eec7a1ba48e.png