Advanced Geometric Problem & Solution (Twice a week update) Now 4874 problems posted.
<Tri-2026-2788>, hint
<Tri-2026-2788>, general, area
<Sweden MO 2010>
<Solid-2026-274>, hint
<Solid-2026-274>, tetrahedron, area
<Sweden MO 2005>
<Solid-2026-273>, hint