Starter quiz
- An ______ angle is an angle formed inside a polygon by two of its edges.
- 'interior' ✓
- Three of the interior angles of a quadrilateral are 80°, 90° and 45°. The size of the fourth interior angle is ______°.
- '145' ✓
- The interior angles of a dodecagon (12 sides) sum to ______°.
- '1800' ✓
- Each interior angle of a regular octagon is ______°.
- '135' ✓
- A regular polygon has interior angles of size 162°. The polygon has ______ sides.
- '20' ✓
- Which interior angles are possible in a regular polygon?
- 154.5
- 156 ✓
- 157.5 ✓
- 160 ✓
-
Exit quiz
- An ______ angle is an angle on the outside of a polygon between an extension of an edge and the adjacent edge.
- 'exterior' ✓
- The exterior angles of any polygon sum to ______°.
- '360' ✓
- An interior angle and its adjacent exterior angle sum to ______°.
- '180' ✓
- The size of each exterior angle of a regular pentagon is ______°.
- '72' ✓
- A regular polygon has exterior angles of 40°. The polygon has ______ sides.
- '9' ✓
- Which of these exterior angles are possible for a regular polygon?
- 30 ✓
- 45 ✓
- 60 ✓
- 75
- 90 ✓
-
Worksheet
Loading worksheet ...
Presentation
Loading presentation ...
Video
Lesson Details
Key learning points
- The sum of the exterior angles of a polygon can be demonstrated using a point.
- The sum of the exterior angles of a polygon can be proven using interior angles and the angles on a straight line.
- An exterior and interior angles pair are supplementary.
Common misconception
An exterior angle is equal to 360° - the size of the interior angle because angles around a point sum to 360°.
An exterior angle is an angle on the outside of a polygon between an extension of an edge and the adjacent edge.
Keywords
Polygon - A polygon is a flat (2D), closed figure made up of straight line segments.
Regular - A regular polygon has sides that are all equal and interior (inside) angles that are all equal.
Interior angle - An interior angle is an angle formed inside a polygon by two of its edges.
Exterior angle - An exterior angle is an angle on the outside of a polygon between an extension of an edge and the adjacent edge.
+