### Teacher Resource

## Interior Angles of a Triangle by Math Open Reference

### Subject

Math, Science & Technology

### Grade Levels

Intermediate, 5th Grade

### Web-based Resource

Access this resource at: http://www.mathopenref.com/triangleinternalangles.html

### Description

This interactive web page demonstrates the properties of the interior angles of a triangle.
The page shows a triangle where the user can drag the vertices to reshape it. As it is being changed, the angles are continually updated, along with an expression showing that they always add to 180°.

The web page can be enlarged to full screen size for use with a classroom projector. After use in the classroom, students can access it again from any web browser at home or in the library with no login required.

### Content Provider

Math Open Reference: http://www.mathopenref.com/

Math Open Reference encourages users to provide feedback, errors, omissions, and ideas for improvement. Please see the feedback link at the top of the page to offer your suggestions.