Exterior and Interior Angles of Regular Polygons All students will be able to calculate the Exterior Angle of a Regular Polygon given the number of sides.

Most will be able to calculate the Interior Angles of a Regular Polygon.

Some will be able calculate the

Sum of Interior Angles. Success Criteria All the exterior angles of a Polygon add up to 360 degrees.

The Interior and Exterior Angles add to 180 degrees.

Also number of triangles

method. How are we going to Calculate these Angles? To understand how to calculate

the Exterior Angles of a Polygon.

Using Exterior Angles, be able to calculate the Interior Angle of a Polygon. Learning Objectives Can you tell me what is a Regular Polygon?

Can anyone guess what is an

Irregular Polygon? What Is A Regular Polygon? What information do we need to find

the Exterior Angles of a Regular Polygon?

How do we calculate the Exterior Angles?

How do we calculate the Interior Angles of the Polygon?

What is a Regular and Irregular

Polygon? To Summarise... Polygon comes from Greek.

Poly- means "many" and -gon means "angle".

A polygon is a two dimensional shape; they are made of

straight lines and the shape is "closed".

There are two types of polygon, regular and irregular. Regular

Octagon Regular

Heptagon Regular

Hexagon Regular

Pentagon Square Equilateral

Triangle

In a regular polygon all lengths and angles are the same size. In an irregular polygon all lengths and angles are different sizes. a + b + c

=

180 degrees! What do angles in a triangle add up to? b c a 360 ÷ 4 = 90°

We can divide a square into two triangles

Two triangles in a square gives a total of:

2 × 180 = 360°

Size of one interior angle is: 90° 90° 90° 90° 540 ÷ 5 = 108°

We can divide a pentagon into three triangles

Three triangles in a pentagon gives a total of:

3 × 180 = 540°

Size of one interior angle is: 108° 108° 108° 108° 108°

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# Interior & Exterior Angles

lesson going over interior and exterior angles for KS3 and KS4

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