University of Illinois at Urbana-Champaign
Office for Mathematics, Science, and Technology Education
College of Education @ University of Illinois

Polygon Sum of Angles

This simulation was designed to allow students to draw different polygons, and then determine the sum of the angles. First, click a few points on the gray canvas to draw a polygon. Finish drawing a polygon by closing it--click back on the first point you created. Then click each of the angles to highlight them. This angle counter will keep track of the sum of all the highlighted angles.

The purpose of this applet is to show that there is a relationship between the number of vertices and the sum of the angles in polygons. See if you can figure it out!


We're sorry, your browser does not support HTML5 Canvas...
Number of Points0
Selected Angle Sum0.00°


  • Original Java Applet by Nick Exner (2000-2003)
  • JavaScript+HTML5 Remake by Evan Ramos (2014)

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