Problem 352. Tangential quadrilateral, Incircles, Common tangent,
Circumscribable or Tangential quadrilateral.
The figure shows a tangential
quadrilateral ABCD with a point E on side BC. Circles 1 and 2
are the incircles of triangles ABE and CDE, respectively. FG is
the common tangent to circles 1 and 2. FG intersects to AE and
DE at M and N, respectively. Prove that the quadrilateral AMND
is circumscribable or tangential (sides all lie tangent to a
single circle inscribed within the quadrilateral).
Geometry problem solving
Geometry problem solving is one of the most challenging skills for students to learn. When a problem requires auxiliary construction, the difficulty of the problem increases drastically, perhaps because deciding which construction to make is an illstructured problem. By “construction,” we mean adding geometric figures (points, lines, planes) to a problem figure that wasn’t mentioned as "given."

Recent Additions
