In this unit we will learn how to construct and 'define' star-shaped polygons. The first part involves a description of how to construct them, using a ruler and compass, although we will be using the computer to draw them. The second part is somewhat more abstract as we discover which conditions we need to produce a star-shaped polygon and which properties it has.

In both parts we use algorithms to give constructive explanations, i.e. we define star-shaped polygons as shapes obtained by following an exact set of instructions. This way of defining geometric shapes is certainly not one of the most familiar methods used but it does lend itself to describing star-shaped polygons. It also allows us to discuss other related areas of interest such as algorithms.

• To understand what algorithms are along with other concepts related to them. 

• To learn how to create simple algorithms.

• To use algorithms to construct star-shaped polygons.