Exterior Angle of a Triangle Worksheet
Explore the properties of exterior angles of triangles with this Grade 9 math worksheet, featuring various problem types.
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Exterior Angle of a Triangle
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Read each question carefully and answer to the best of your ability. Show all your work for full credit.
The exterior angle of a triangle is equal to the sum of the two opposite interior angles.
1. In the triangle below, find the measure of the exterior angle x.
2. An exterior angle of a triangle measures 120°. If one of the opposite interior angles is 50°, what is the measure of the other opposite interior angle?
3. Which of the following statements is true regarding the exterior angle of a triangle?
It is always acute.
It is equal to the sum of the adjacent interior angles.
It is equal to the sum of the two opposite interior angles.
It is always less than 90°.
4. The sum of the interior angles of any triangle is always degrees.
5. An exterior angle and its adjacent interior angle are angles, meaning they sum to 180°.
6. The exterior angle of an equilateral triangle is 120°.
True
False
7. The exterior angle theorem applies only to right-angled triangles.
True
False