Geometry Help
Geometry Help: Inscribed Shapes
Explains the basic concept of inscribed shapes with step-by-step instructions and methods for solving specific problems on your own relating to this topic.
Geometry Help
Geometry Help: Circles
Explains the basic concept of circles with step-by-step instructions and methods for solving specific problems on your own relating to this topic.
Geometry Help
Geometry Help: Square Inscribed in a Circle
Explains the basic concept of a square inscribed in a circle with step-by-step instructions and methods for solving specific problems on your own relating to this topic.
Math Open Reference
Math Open Reference: Circumcircle of a Triangle
A complete reference guide to the circumcircle of a triangle. It provides definitions, examples, and an interactive activity that enhances further explanation. Includes links to related topics.
Khan Academy
Khan Academy: Inscribed Quadrilaterals
Use the fact that opposite angles in an inscribed quadrilateral are supplementary to solve a few problems.
CK-12 Foundation
Ck 12: Interactive Geometry: 8.5 Inscribed and Circumscribed Circles of Triangle
Learn how an inscribed circle is the largest circle contained within the triangle.
CK-12 Foundation
Ck 12: Interactive Geometry: 8.4 Inscribed Angles
Learn about inscribed angles formed by two chords in a circle which have a common endpoint.
CK-12 Foundation
Ck 12: Interactive Geometry: 8.6 Quadrilaterals Inscribed in Circles
Understand that quadrilaterals that can be inscribed in circles are known as cyclic quadrilaterals.
Khan Academy
Khan Academy: Challenge Problems: Inscribed Shapes
Solve three challenging problems that apply properties of inscribed shapes to find an arc length or a missing angle.
National Council of Teachers of Mathematics
The Math Forum: Conic Sections/circles
This site provides a catalog of Web sites and Web pages that deal with circles.
University of Georgia
University of Georgia: Altitudes & Orthocenters: Making Connections
This site describes altitudes and orthocenters in triangles and their connections with the nine-point circle.
Wolfram Research
Wolfram Math World: Circles
This site provides definitions for a wide range of topics dealing with circles.
Math Words
Mathwords: Inscribed Circles
Mathwords provides an explanation and a diagram of an inscribed circle. By clicking on any of the highlighted words, you will learn about related terms.
Maths Challenge
Maths challenge.net: Cables
This is a proof problem, considered a "three star" geometry problem requiring knowledge of proofs and properties of circles to solve this problem with cables in duct problem.
Maths Challenge
Maths challenge.net: Radical Axis
This is a "three star" geometry problem requiring knowledge of proofs and properties of circles. Students will use the given definition of radical axis and prior knowledges to prove a way to find a radical axis.
Shmoop University
Shmoop: Basic Geometry: Circles
The geometry resource explores the different parts of a circle. Definitions and examples are included.
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...
Walter Fendt
Walter Fendt: Thales' Circle
A short interactive activity to prove that a triangle inscribed in a semicircle is right-angled.
Walter Fendt
Walter Fendt: Tangential Quadrilateral (Circumscribed Quadrilateral)
A short interactive activity which allows you to move the vertices of a quadrilateral circumscribed around a circle.
Walter Fendt
Walter Fendt: Cyclic Quadrilateral (Inscribed Quadrilateral)
A short interactive activity which allows you to move the vertices of a quadrilateral to prove that the sum of the opposite angles is 180 degrees.
Ducksters
Ducksters: Kids Math: Triangles
Learn about equilateral, right angle, and isosceles triangles on this site. Learn how they work, terms, tricks and examples. .
Math Open Reference
Math Open Reference: Circumcircle
A handy reference guide to circumcircles. It provides definitions and examples that enhance further explanation. Includes links to related topics.
Math Open Reference
Math Open Reference: Square Inscribed in a Circle
Learn about a square inscribed in a circle with this handy reference guide. Provides a detailed definition and an interactive activity that enhances further explanation. Includes links to related topics.