1. Triangle Sum Theorem
By: Jeffrey McAven

2. Triangle What is the measure of the interior angles of a Triangle?
180°

3. Rectangle What is the measure of the interior angles of a Rectangle?
Hint: How many triangles are there in a rectangle?
180°
180°
360° (180 for each triangle)

4. Does this work for ANY shape
Any ideas how I might find the measure of the Interior angles for a random figure?
3 triangles
540°
4 Triangles
720°

5. What is the Formula? (n-2)180 = the sum of the interior angles
After talking about the previous slides can you think of a possible formula?
(n-2)180 = the sum of the interior angles
n is the number of sides on any figure
Regular polygon: all sides and angle measurements are equal.

6. Lets Practice shall we..... 4 Sides (4-2)180 = 360
Tell me how many triangles and what the sum on the interior angles would be.
4 Sides
(4-2)180 = 360

7. Now what if I just tell you the amount of side??
(10-2)180 = 1,440
Decagon (10 sides)
Nonagon (9 sides)
Dodecagon (12 Sides)
18-gon
(9-2)180 = 1,260
(12-2)180 = 1,800
(18-2)180 = 2,880