Sum of Interior Angles and
Exterior Angles
Sum of Interior Angles of a Polygon
180(n-2)
Where n is the number of sides
Interior angles are the angles inside the Triangle
If the polygon is regular you can find each
interior angle
180(n-2)/n
Exterior Angles of a Polygon
The sum of the exterior angles of a polygon is
always 360
Exterior angles are the angles outside a polygon,
paired with one interior angle making linear
pairs
If the polygon is regular then you can find each
interior angle 360/n
Know which equation to use when
The sum of the interior angles of a polygon is
720, how many sides does it have.
720 is a sum
180(n-2)=720
Solve equation for n
More
Each exterior angle of a regular polygon is 30,
how many sides does it have.
30 is an exterior angle
360/n=30
More
If the sum of the interior angles of a regular
polygon is 4000, what is the measure of each
exterior angle.
2 steps
Given sum and find exterior
180(n-2)=4000
Solve for n
360/n=each exterior
Homework
Wkst on these two topics cross out last problem
on each page