This site is for the purpose of using proofs for geometry. It helps by giving some useful theorems.

Betty Fei details these three famous Pythagorean theorem proofs.

An explanation and proof of the Four Color Map Theorem. Includes illustrative images and a plethora of information.

The introduction of this lesson has students verifying the famous Pythagorean Theorem with a hands-on proof. Students will then apply the Theorem in one of two ways: by solving for the side lengths of a right triangle and by determining...

[Free Registration/Login may be required to access all resource tools.] Prove a quadrilateral is a parallelogram.

This short lesson focuses more on the angle bisector theorem. Learn about the angle bisector theorem proof, triangle angle bisector theorem, how to construct angle bisector, and other interesting properties and facts around angle bisectors.

This mini-lesson explores the world of the midsegment of a triangle by finding the answers to questions like what is midsegment of a triangle, triangle midsegment theorem, and proof with the help of interactive questions.

This lesson explores triangle inequality theorem, triangle inequality theorem-proof, and triangle inequality theorem problems. Try the hands-on triangle inequality theorem calculator and interactive problems to have a better...

This tutorial discusses triangle inequality and provides practice problems for students to try out their skills. The teacher resource page contains a lesson plan for a yummy activity involving licorice.

In this lesson, learn all about the 30-60-90 triangle. Learn about its sides, its area, and the rules that apply to these triangles. Includes simulations and practice questions.

Explore the world of the hypotenuse leg theorem in this mini-lesson. Provides a definition, examples, and practice questions with answers that help with understanding their properties.

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

Students are given a conitional statement and are to determine which choice is the converse of the statement.

Use your right triangle solving skills to solve this ladders in a hole problem.

Use your knowledge of volume and weight to solve this posed problem of finding the weight of a glass in a door.

A realistic world problem using the knowledge of chords and the parts of a circle to solve. Test your knowledge on this brain teaser!

Is summer close yet? Think about this yummy ice cream treat in a mathematical way! A problem of volume is posed for an ice cream cone.

Find the area of this triangle in a coordinate plane.

Use your triangle solving skills to solve this triangle problem and then apply it to the real world.

A problem involving patterns to find the solution to this sequence problem.

An area problem using your knowledge about pentagons.

A lune of a circle is defined and a problem of finding the area of two lunes is given.

This standards-based NCTM website offers resources for teachers of mathematics for all grade levels, including interactive math tools, lesson plans, online resources, and the like.

An area problem involving diagonals of a tiled floor.