ClassFlow
Class Flow: Circles and Angles
[Free Registration/Login Required] In this flipchart students practice identifying parts of a circle, measure angles, and practice solving area and circumference problems.
Shmoop University
Shmoop: Basic Geometry: Circles
The geometry resource explores the different parts of a circle. Definitions and examples are included.
Sonoma State University
Sonoma State University: Angle Bisector
This site offers an explanation with words and pictures on how to bisect an angle using a compass and straightedge.
National Council of Teachers of Mathematics
The Math Forum: Problems Library Geometry Triangles
This site contains a wealth of problems that deal with the basic definitions of medians, altitudes, angle bisectors, and perpendicular bisectors or the defining characteristics of the different types of triangles. There are also...
University of Georgia
University of Georgia: Inter Math: Inscribed Angle
This site gives a description of inscribed angles along with a visual representation. There are links to related terms, challenging problems, more information, and the interactive check point involving inscribed angles located in the...
University of Georgia
University of Georgia: Inter Math: Angle Bisector
This site provides a general definition, complete with a diagram, of an angle bisector.
Walter Fendt
Walter Fendt: Thales' Circle
A short interactive activity to prove that a triangle inscribed in a semicircle is right-angled.
Wolfram Research
Wolfram Math World: Inscribed Angle
This site provides not only a definition of inscribed angle but also links to related terms.
Oswego City School District
Regents Exam Prep Center: Formulas for Angles in Circles
Formulas and illustrations show the different kinds of angles created by intersecting tangents, secants, radii, and in combination.