- Mathew Purser
To describe a circle with any center and radius. Circles can be drawn with two pieces of information, the center and a point on the circumference of the circle. Since we can a compass to draw a circle and the radius of a circle is constant, we can use circles to copy lengths to different parts of a figure.
Use the tool to draw a circle with center A and radius AB. Use the tool to "measure" the distance from C to D, then use that circle to draw a line out of E that is the same length of CD. Remember! The radius of a circle is constant. Play around with the tools until you are comfortable.