In this activity, students learn about the sum of the angles in a triangle. They understand triangles and their interior angles.

Reviews the rule that the interior angles of a triangle always add up to 180 degrees. Includes three practice problems.

MathWorld offers a definition for an interior angle bisector accompanied by an example this site also gives a formula for the lenght of the bisector of a triangle.

A reference guide to obtuse triangles. It provides a definition and interactive animated activity that enhances further explanation.

Given examples of triangles and their component parts, the student will use explorations and concrete models to verify and apply the and find the sum of interior angles.

Use your knowledge of angles to find missing angle measures in various complex situations. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video, or receive hints.

This activity uses the graphing calculator to show the relationship between an exterior angle of a triangle and the two remote interior angles.

Learn how similar triangles have congruent corresponding angles and proportional corresponding sides.

[Free Registration/Login may be required to access all resource tools.] Find interior angle measures of polygons by drawing diagonals to create triangles.

This activity is designed as an introduction to using the Carbri Jr. application on the TI-83+/84+ calculators. Students are guided through the menu system and are shown how to draw triangles, quadrilaterals and and a pentagon. Perimeter...

Get the definition and properties of a polygon. Then explore such topics as: 1) types of polygon 2) area 3) Perimeter 4) angles associated with polygons and 5) names of polygons.

Find a quick, concise explanation of the Angle Sum Theorem. A step by step explanation of the proof is included to help you understand the theorem.

[Free Registration/Login may be required to access all resource tools.] This study guide focuses on polygons: convex vs concave, interior and exterior angles, and basic terminology for common polygons.

[Free Registration/Login Required] This lesson covers methods of classifying triangles, both according to the length of their sides and by the measure of their interior angle.

[Free Registration/Login Required] In this Flipchart, students explore linear pairs and vertical angles. Students determine the measure of interior and exterior angles.