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.
• The sum 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.

Examples 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

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.

Related Terms for Exterior Angle

• Adjacent Sides
• Alternate
• Alternate Exterior Angle
• Interior Angle.

Additional Links for Exterior Angle

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