2.2 Angle Sums of ANY Polygon

Objective:

To develop a formula to helps us find the sum of the interior angles for ANY polygon with n sides.

Last class we looked at a strategy that we could use to find the sum of the angles for regular polygons.  In this class, we are going to build on that idea and try to extend our pattern to include all polygons.

Do Now:

On the piece of paper provided complete the following tasks:

• draw an angle of 60 degrees
• determine the complement and supplement of the angle that you drew.
• measure all three angles of the triangle and add them together.  Compare with the others in your group.  What do you notice?

Explore:

What is the sum of the angles in a quadrilateral?  How can we use the "Angle Sum of a Triangle" to prove this?

Problem 2.2 Tasks B and C

Glue Labsheet 2.2 in your squarebook.  You will do all of your work for these tasks on this Labsheet.

Trevor's Method:

Casey's Method:

At the end of this Problem you should be able to do the following:

• Use a formula to determine the angle sum of any polygon.
• Explain the meaning of each formula discovered in this lesson.

Homework:

• ACE Problems (3, 4, 5 ,6, 7, 8,9 10, 11) (19) (23, 24)