2009
Van Aubel's Theorem: 11328 [2007, 925].
Am. Math. Mon., 2009

From Quadrilateral to Trapezoid: 11317 [2007, 745].
Am. Math. Mon., 2009

Problem 11449.
Am. Math. Mon., 2009

2008
Perimeter by Integral: 11256.
Am. Math. Mon., 2008

A Permanent Lower Bound: 11253.
Am. Math. Mon., 2008

If AB Preserves A, then BA Preserves B: 11239.
Am. Math. Mon., 2008

2007
Finding the Greatest Lower Bound: 11217.
Am. Math. Mon., 2007

Counting Lattice Quadrilaterals Tangent to an Ellipse: 11163.
Am. Math. Mon., 2007

Problem 11317.
Am. Math. Mon., 2007

2006
Simple Roots for Polynomials: 11094.
Am. Math. Mon., 2006

Problem 11239.
Am. Math. Mon., 2006

Problem 11217.
Am. Math. Mon., 2006

2005
Morley's Triangle and Lemma: 11038.
Am. Math. Mon., 2005

A Combinatorial Sum Goes on Tangent: 11044.
Am. Math. Mon., 2005

Problem 11163.
Am. Math. Mon., 2005

2004
Problem 11094.
Am. Math. Mon., 2004

2003
A Root Inequality: 10944.
Am. Math. Mon., 2003

Problem 11044.
Am. Math. Mon., 2003

2000
A Differential Equation with Many Solutions: 10747.
Am. Math. Mon., 2000