Stephen ARNOLD
HomeOnLine Maths Resources →The Case of the Diminishing Square

The Case of the Diminishing Square

A small square EFGH is constructed within a larger (unit) square, OABC, as shown.

The point W gives the position of the defining point D and the AREA of the smaller square.

Can you find an algebraic model which best describes this relationship?

Drag the point D to explore this problem.

Build an algebraic model for the area of the smaller square by defining the following function:

dimsquare(x) =


My name:

My class:

Teacher Email:

Steve Arnold, 2018, Created with GeoGebra


This problem may also be modelled using CabriJr on the TI-83/84 series calculator. Click on the graphic below to download the file and try it yourself!

Try having students work in pairs: one generating data points using the CabriJr model and the partner entering these into lists to plot and then to help build their algebraic model!


Just wait until you try this with TI-nspire CAS!

And you may want to have a look at Geometry Expression.

©2018 Compass Learning TechnologiesLive Mathematics on the Web ← GeoGebra Showcase