From NCTM's September 2016 issue of Mathematics Teacher
What fractional part of the regular pentagram is shaded?
Given Answer: 1/2
A regular pentagram can be decomposed into triangular regions as colored in the figure below. The yellow and turquoise triangles are congruent. The problem's shaded region consists of two turquoise triangles, one yellow triangle and one red triangle, as does the unshaded region.