mythematics
  • Home
  • About
  • Contact

Challenge #05

International Paper

A sheet of A4 paper (which is used commonly outside of the USA) has the following interesting property: when folded in half along its longest dimension, the smaller rectangle is mathematically similar to the original rectangle.
​
What fraction of a sheet of A4 paper lies inside the largest circle that can be drawn on that sheet of paper?

Follow-up Challenges

If the original piece of paper is a square, what fraction of the paper lies inside the largest circle that can be drawn on the paper?

What if the original piece of paper is a golden rectangle?

Describe the dimensions of a sheet of paper such that exactly one-third of the paper is inside the largest circle that can be drawn. Can you find a real piece of paper that (approximately) fits your description?

A correspondent from Austin, Texas wondered whether it is possible to construct an "A4 rectangle" with compass and straightedge. What do you think?

Response Videos

Marissa's response video
Except where otherwise noted, content on this site is by Jason Ermer and licensed under
​a Creative Commons Attribution-Noncommercial 4.0 International license (
CC BY-NC 4.0).
  • Home
  • About
  • Contact