MathDB
equal circles wanted

Source: 2023 Belgium, VWO Flanders MO p2

March 25, 2024
geometryequal circles

Problem Statement

In the plane, the point MM is the midpoint of a line segment [AB][AB] and \ell is an arbitrary line that has no has a common point with the line segment [AB][AB] (and is also not perpendicular to [AB][AB]). The points XX and YY are the perpendicular projections of AA and BB onto \ell, respectively. Show that the circumscribed circles of triangle AMX\vartriangle AMX and triangle BMY\vartriangle BMY have the same radius.