Explore everything about circles. Learn various parts of a circle like a diameter, radius, circumference, circles chord, tangent circles, major arc, segment, sector, and discover other interesting aspects of it. Try your hand at solving...

The Math Forum offers an archive of question and answer sessions on circles and how they relate to geometry.

Learn about a line that intersects a circle in two points is called a secant line.

Understand that quadrilaterals that can be inscribed in circles are known as cyclic quadrilaterals.

Learn about inscribed angles formed by two chords in a circle which have a common endpoint.

Learn how similarity transformation is one or more rigid transformations (reflection, rotation, translation) followed by a dilation.

Practice interesting area and circumference problems. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.

This reference tool explores the radius of a circle. Provides definitions, solved examples, and practice questions with answers.