Angles of Polygons

Angles of Polygons

Interior Angle Sum

Names of Polygons

• A 3-sided polygon is called a TRIANGLE

• A 4-sided polygon is called a QUADRILATERAL

• A 5-sided polygon is called a PENTAGON

• A 6-sided polygon is called a HEXAGON

• A 8-sided polygon is called a OCTAGON

• A 9-sided polygon is called a NONAGON

• A 10-sided polygon is called a DECAGON

Multiple Choice

How many sides does a hexagon have?

• 4

• 5

• 8

• 6

Multiple Choice

How many sides does a pentagon have?

• 4

• 5

• 8

• 6

Multiple Choice

How many sides does a nonagon have?

• 9

• 5

• 8

• 6

Finding the Interior Angle Sum

• To find the interior angle sum of a polygon, we follow two easy steps.

• First, take the number of sides and subtract two. In our formula this will appear as $\left(n-2\right)$   with n being the number of sides.

• Second, multiply by 180.

•  $Interior\ Sum\ =\ 180\left(n-2\right)$  

Find the Interior Angle Sum of a Pentagon

Multiple Choice

Find the Interior Angle Sum of a Hexagon

• 360

• 720

• 1080

• 1260

Multiple Choice

Find the Interior Angle Sum of an Octagon

• 360

• 720

• 1080

• 1260

Find the Measure of One Interior Angle

• If we want to find the measure of ONE angle in a shape instead of the sum, we use this formula: $\frac{Sum}{Sides}$   

• First find the sum of the interior angles, then divide by the number of sides.

Find the Measure of an Interior Angle in a Regular Pentagon

Multiple Choice

Find the measure of an interior angle in a regular triangle.

• 60

• 120

• 135

• 90

Multiple Choice

Find the measure of an interior angle in a regular hexagon.

• 60

• 120

• 135

• 90

Multiple Choice

Find the measure of an interior angle in a regular octagon.

• 60

• 120

• 135

• 90