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Exterior Angle Theorem Worksheet

Practice problems for grade 8 students on the Exterior Angle Theorem, including finding unknown angles and applying the theorem to various triangles.

Grade 8 Math GeometryExterior Angle Theorem
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Includes

Multiple ChoiceFill in the Blanks2 Short AnswerTrue / False

Standards

CCSS.MATH.CONTENT.8.G.A.5

Topics

mathgeometryexterior angle theoremtrianglesanglesgrade 8
7 sections · Free to use · Printable
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Exterior Angle Theorem Practice

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Read each question carefully and use the Exterior Angle Theorem to solve for the unknown angle(s). Show your work where indicated.

1. In the triangle below, what is the measure of the exterior angle labeled x?

A60°70°x
a

110°

b

120°

c

130°

d

140°

2. The Exterior Angle Theorem states that the measure of an exterior angle of a triangle is equal to the sum of the measures of its two   interior angles.

3. If the two remote interior angles of a triangle are 45° and 85°, then the exterior angle is  .

4. In a triangle, if one remote interior angle is 55° and the exterior angle is 120°, what is the measure of the other remote interior angle? Show your work.

5. The exterior angle of a triangle is always greater than either of its remote interior angles.

T

True

F

False

6. Consider a triangle with interior angles (2x + 10)°, (3x - 5)°, and 75°. Find the value of x and the measure of the exterior angle adjacent to the 75° angle. Show all steps.