This site has many useful formulas and examples relating to circles, including related definitions, circumference of a circle, area of a circle, length of a circular arc, area of a circular sector, equation of a circle in cartesian...

Learn about drawing shapes using only a compass and straight edge or ruler with out measuring any lengths or angles.

Determine the circumference of a circle or simple arc lengths.

Try these three problems regarding area of sectors, length of arcs, and central angles. The problems will challenge and intrigue sharp geometry students. Detailed written solutions are included.

Solve two challenging problems that apply the inscribed angle theorem to find an arc measure or an arc length.

Practice the relationship between inscribed and central angles that are subtended by the same arc length. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.

Solve three challenging problems that apply properties of inscribed shapes to find an arc length or a missing angle.

Goes over the equation of a circle, parametric equations of a circle, intersection of circle and line, tangent line in a point of a circle, etc.