external image crop_circles_swirl.jpg
Interior angle sum of a polygon

A polygon is any closed shape with straight sides. Examples include:


external image 5polygons.png
The following are not polygons

external image nonpolygon.jpg

Interior angle sum means all of the angles inside the shape added up. Like the interior angle sum of a triangle is 180°.
  • Follow the teachers' instructions to complete an activity using Geogebra to find the interior angle sum of a polygon.

The formula for the interior angle sum of any polygon is:

ANGLE SUM=


  • Find the interior angle sum of the following polygons:
a)
external image shape-rectangle.gif
angle sum=
n=
angle sum =
=

b)
external image hexagon.png
angle sum=
n=
angle sum =
=

c)
external image polygon.gif







  • Mathletics

  • If you have completed your work, have a go at the following matching game. In this game, you will match shapes and their names.

http://www.mathplayground.com/Matching_Shapes.html