Geometric shapes are all around us. The world is built with them. In this series of tutorials and exercises you'll become familiar with Euclidean geometry and terms like segments, scale drawings, parts of a circle, area, volume, angles, and geometric figures.
Area and circumference of circles
A circle is at the foundation of geometry, and at the foundation of a circle is a special number called Pi. This number allows us to relate the radius, diameter, and circumference of a circle.