Play the animation or move the slider for \(b\). What do you notice? What questions do you have?

You might have noticed that when \(b = 1\), all the pentagons are the same size. This suggests something multiplicative. In fact \(b\) is the scale factor between the each sized regular pentagon. I.e. when \(b = 0.5\) the side length of each pentagon will be half the length of the previous pentagon.

You might like to think about some of the following questions for different values of \(b\). For example, when \(b = 0.38, 0.5, 1\).

  • How many regular pentagons can you see?
  • What fraction of the shape is shaded in each different colour?
  • Can you find the area of any of the shapes?
  • Can you see any sequences in the diagram?
  • Can you make any links to geometric series? (You may wish to look at Square spirals if you haven’t already done so.)