What Are Compound Shapes?
Look around you — most real-world shapes are not simple rectangles or squares. A swimming pool might have a step section at one end. A room might have a bay window alcove. A park might be L-shaped. These are all examples of compound shapes (also called composite figures).
A compound shape (or composite figure) is any 2D shape made up of two or more basic shapes joined together. The word composite literally means 'placed together'.
The great news is that even the most complicated-looking compound shapes can always be broken down into basic shapes — rectangles, squares, triangles — that you already know how to work with.
Think of a compound shape like a LEGO structure. No matter how complex the build looks, it is always made from individual, simple bricks. To understand the whole thing, you just need to identify the individual pieces.
Quick Review: Area and Perimeter of Basic Shapes
Before tackling compound shapes, let's make sure the basics are solid.
The perimeter of a shape is the total distance around the outside. It is found by adding all the side lengths together. Units are always length units, e.g. cm, m.
The area of a shape is the amount of flat space it covers. Units are always squared, e.g. cm², m².
For a rectangle:
For a square (special rectangle where ):
Rectangle on squared paper:
A rectangle has length 5 cm and width 4 cm.
Always write the unit with your answer! Area uses squared units (cm²), and perimeter uses plain length units (cm). Forgetting this is one of the most common mistakes in assessments.
9 more sections in this topic
Pick this up in your Library: it holds the whole topic, notes, cheatsheet and questions.