Illustrative Mathematics
Lines of Symmetry for Circles
Further your instruction on geometrical symmetry with an investigation of circles. Fourth graders come to realize that the lines of symmetry of a circle are infinite.
Government of Alberta
Learn Alberta: Math Interactives: Exploring Circle Geometry Properties
Investigate circles, namely their angles, chords, and tangents using this highly interactive Learn Alberta math. Explore a number of circle geometry properties that can be used to determine unknowns. Be sure to follow the link to the...
Math Open Reference
Math Open Reference: Circle
Learn about circles with this handy reference guide. Provides a detailed definition, examples, and interactive activities that enhance further explanation. Includes links to related topics.