Exterior Angle Property Worksheet
Grade 9 math worksheet focusing on the exterior angle property of triangles, including multiple choice, fill-in-the-blanks, and short answer questions.
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Topics
Exterior Angle Property
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Read each question carefully and answer to the best of your ability. Show all your work for short answer questions.
1. What is the exterior angle property of a triangle?
The sum of interior angles is 180°.
An exterior angle is equal to the sum of the two opposite interior angles.
All angles in an equilateral triangle are 60°.
The sum of an interior angle and its adjacent exterior angle is 90°.
2. In a triangle, if two interior angles are 50° and 70°, what is the measure of the exterior angle adjacent to the third interior angle?
60°
120°
130°
180°
3. The sum of the three exterior angles of any triangle is always .
4. An exterior angle of a triangle is formed by extending one of its .
5. The exterior angle property is a direct consequence of the sum property of a triangle.
6. Consider a triangle ABC. If ∠A = 65° and ∠B = 45°, find the measure of the exterior angle at vertex C. Show your work.
7. An exterior angle of a triangle is 110°. If one of the interior opposite angles is 60°, what is the measure of the other interior opposite angle? Show your work.
8. The exterior angle property applies only to right-angled triangles.
True
False
9. An exterior angle and its adjacent interior angle are supplementary.
True
False