Learn to use the Pythagorean Theorem with non-right triangles. Pupils use the interactive to discover the relationship between the lengths of sides for acute and obtuse triangles. They compare the squares of the sides of the triangles to...

How do you build a polygon from an inequality? An engaging lesson challenges pupils to do just that. Building from the previous lesson in this series, learners write systems of inequalities to model rectangles, triangles, and even...

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.

This lesson focuses on the Triangle Inequality, when the sum of the lengths of any two sides of a triangle is greater than the length of the third. When this happens, the three sides cannot form a triangle.