# Polygons: Sum of Exterior Angles

- Author:
- Alex Fetterman, Tim Brzezinski

The exterior angles of a triangle, quadrilateral, and pentagon are shown, respectively, in the applets below.
Control the size of a colored exterior angle by using the slider with matching color.
Move the vertices of these polygons anywhere you'd like.
For the

**quadrilateral**&**pentagon**, the last two applets work best if these polygons are kept**convex.**If you don't remember what this term means, click here for a refresher.## Exterior Angles of a Triangle

## Exterior Angles of a Quadrilateral

## Exterior Angles of a Pentagon

## 1.

What do you notice? What is common about the measures of the exterior angles of any one of these polygons?

## 2.

Do you think what you've observed for the triangle, quadrilateral, and pentagon above will also hold true for a hexagon, heptagon, and octagon? Make a conjecture about the sum of exterior angles of a convex polygon: