Exterior Angle
Definition Of Exterior Angle
An Exterior Angle of a polygon is the angle formed when one side is extended beyond its adjacent sides.
When two lines are cut by a third line (transversal), then the angles formed outside the lines are called Exterior Angle.
More About Exterior Angle
The number of exterior angles in a polygon = The number of sides of the polygon
The exterior angle is supplemental to the adjoining interior angle.
Thesum of the measures of exterior angles of a convex polygon is 360°.
Measure of the exterior angle of a triangle is equal to the sum of its two remote angles.
Video Examples: Angles in polygons- exterior angles
Example of Exterior Angle
∠1, ∠2, and ∠3 are the exterior angles.
∠4, ∠5, ∠6, and ∠ 7 are the exterior angles.
Solved Example on Exterior Angle
Ques: Identify the pair of exterior angles in the figure.
Choices:
A. 1 and 2
B. 2 and 4
C. 1 and 3
D. 3 and 4
Correct Answer: C
Solution:
Step 1: An Exterior Angle of a polygon is the angle formed when one side is extended to its adjacent sides.
Step 2: From the figure, the angles 1 and 3 are exterior because one side is extended to its adjacent sides.
Step 3: So, 1 and 3 is a pair of exterior angles.
- Exterior-Angle-Theorem-Gr-8