A-5 deals with patterns found in * POLYGONS*, which are two-dimensional (or “

*plane”*) closed figures consisting of line segments (or lines) as sides. Triangles are polygons. So are quadrilaterals, pentagons, etc. Circles are not.

# Guided Practice:

Each question in Guided Practice has a walk-through of the solution. Command-Click the “help” button to open the walk-through in a new window.

1. Find the sum (total) of the interior angles of a 40-sided polygon (40-gon)

2. Find the measure of each angle of a *regular* 90-gon. (NOTE: A *regular* polygon is a polygon where every side has the same length and every angle has the same measure)

3. Find the measure of each exterior angle of a regular 45-gon. (NOTE: An exterior angle is the difference between 180 degrees and an interior angle. Basically, what makes up a straight line with the interior angle)

# Practice Problems:

## Answer Key