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Exterior Angle of a Triangle Worksheet

Explore the properties of exterior angles of triangles with this Grade 11 worksheet, including solving for unknown angles and applying the Exterior Angle Theorem.

Grade 11 Math GeometryExterior Angle of a Triangle
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Includes

2 Short AnswerFill in the BlanksMultiple ChoiceTrue / False

Standards

CCSS.MATH.CONTENT.HSG.CO.C.10

Topics

mathgeometryexterior angletrianglegrade 11
7 sections · Free to use · Printable
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Exterior Angle of a Triangle

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Read each question carefully and show all your work. Use the provided diagrams to help you visualize the problems. Remember, 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 at vertex C. The interior angles are A = 70° and B = 50°.

ABC70°50°x

2. The exterior angle of a triangle is equal to the sum of the two   interior angles.

3. If an exterior angle of a triangle measures 120° and one of the opposite interior angles measures 75°, then the other opposite interior angle measures  .

4. Which of the following statements is true regarding the exterior angle of a triangle?

a

It is always acute.

b

It is equal to the adjacent interior angle.

c

It is equal to the sum of the two opposite interior angles.

d

It is always greater than 180°.

5. In triangle XYZ, the exterior angle at Y is 145°. If angle X is 60°, find the measure of angle Z.

XYZ60°145°

6. The sum of the exterior angles of any triangle is always 360°.

T

True

F

False

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