MathDB
Math Prize 2021 Problem 19

Source:

September 20, 2021
Math Prize for Girlsgeometry3D geometrytetrahedron

Problem Statement

Let TT be a regular tetrahedron. Let tt be the regular tetrahedron whose vertices are the centers of the faces of TT. Let OO be the circumcenter of either tetrahedron. Given a point PP different from OO, let m(P)m(P) be the midpoint of the points of intersection of the ray OP→\overrightarrow{OP} with tt and TT. Let SS be the set of eight points m(P)m(P) where PP is a vertex of either tt or TT. What is the volume of the convex hull of SS divided by the volume of tt?