MathDB
Folded Paper Cutting

Source:

March 9, 2008

Problem Statement

A piece of paper is folded in half. A second fold is made at an angle ϕ \phi (0<ϕ<90 0^\circ < \phi < 90^\circ) to the first, and a cut is made as shown below. 12881 When the piece of paper is unfolded, the resulting hole is a polygon. Let O O be one of its vertices. Suppose that all the other vertices of the hole lie on a circle centered at O O, and also that \angle XOY \equal{} 144^\circ, where X X and Y Y are the the vertices of the hole adjacent to O O. Find the value(s) of ϕ \phi (in degrees).