The converse of the Pythagorean Theorem is examined through examples and a video lesson. [1:04]

[Free Registration/Login may be required to access all resource tools.] This concept teaches students the Triangle Inequality Theorem and how to apply it.

This study guide on triangle inequalities discusses comparing angles and sides, the Triangle Inequality Theorem, and the Hinge Theorem. It is available for download with free registration.

[Free Registration/Login may be required to access all resource tools.] This concept introduces students to the Third Angle Theorem.

[Free Registration/Login may be required to access all resource tools.] Apply the Triangle Inequality Theorem to determine if three side lengths make a triangle.

[Free Registration/Login may be required to access all resource tools.] This concept teaches students the midsegment theorem and how to apply it.

[Free Registration/Login may be required to access all resource tools.] Apply the Midsegment Theorem.

[Free Registration/Login may be required to access all resource tools.] Provides an overview of triangle congruence, including key terms, properties of congruent triangles, triangle postulates and theorems, and special triangles.

This study guide on angles and transversals covers key terms, angle types formed by transversals, postulates and theorems about transversals, and how to prove if lines are parallel or perpendicular. It is available for download with free...

[Free Registration/Login may be required to access all resource tools.] Learn about the Inscribed Quadrilateral Theorem and solve problems involving quadrilaterals inscribed in circles.

[Free Registration/Login may be required to access all resource tools.] Looks at how to apply the Intersecting Chords Theorem.

Here is a challenging problem for anyone with an interest in geometry. This project requires background research to solve it, but it is an excellent illustration of visual thinking in mathematics.

[Free Registration/Login may be required to access all resource tools.] Identifying and applying theorems to determine triangle congruence.

[Free Registration/Login may be required to access all resource tools.] Apply parallelogram theorems.

[Free Registration/Login may be required to access all resource tools.] This study guide looks at the definitions and units for perimeter, area, and circumference, and at the perimeter and area of different shapes, including regular...

This study guide on lines and angles covers key terminology; line notation; parallel, perpendicular, and skew lines; and postulates and theorems about lines. It is available for download with free registration.

[Free Registration/Login Required] Students explore the concept of the exterior angles theorem by navigating through the interactive learning module and then answering questions that go along with the module. Students can also learn more...

Use the Angle Bisector Theorem to find missing side lengths in triangles. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.

[Free Registration/Login may be required to access all resource tools.] This concept teaches students properties of and theorems about parallelograms and how to apply them.

[Free Registration/Login may be required to access all resource tools.] This concept teaches students how to determine if lines in triangles are parallel and find missing lengths using the Triangle Proportionality Theorem.

[Free Registration/Login may be required to access all resource tools.] This concept teaches students about polyhedrons, Euler's Theorem, and regular polyhedrons.

[Free Registration/Login may be required to access all resource tools.] Apply Euler's Theorem.

[Free Registration/Login may be required to access all resource tools.] Use the SSS Similarity Theorem to determine if triangles are similar.

[Free Registration/Login may be required to access all resource tools.] Apply the Median Theorem.