__Question__

What is your favourite computer game?

How long do you spend playing it?

Do you know that calculating angles within computer games and graphics is extremely important?

Interior and exterior angles are used in compiling 3D graphics.

Lets remind ourselves of how to find the angles.

__The rule for finding ____internal____ angles__

number of sides - 2 x 180 ÷ number of sides

e.g to find the internal angle of a pentagon

5 - 2 = 3

3 x 180 = 540° in the pentagon

540 ÷ 5 = 108° internal angle

__The rule for finding ____external____ angles__

Let us look at the rule for internal and external angles.

Example

Find the interior and exterior angle of this heptagon.

__Interior__

7 - 2 = 5

5 x 180 = 900

900 ÷ 7 = 128.5°

Exterior

360 ÷ = 51.5°

Check

128.5° + 51.5° = 180°

Time to get off the computer games and get to work.