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Exterior Angle Property of Triangles

Explore and apply the exterior angle property of triangles to solve for unknown angles in various geometric figures.

Grade 11 Math GeometryExterior Angle Property
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Includes

3 Short AnswerFill in the BlanksMultiple ChoiceTrue / False

Standards

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

Topics

GeometryTrianglesExterior AngleGrade 11
8 sections · Free to use · Printable
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Exterior Angle Property of Triangles

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Read each question carefully and use the exterior angle property of triangles to find the unknown angles. Show all your work.

1. State the Exterior Angle Property of a Triangle in your own words.

ABC60°70°x

2. In the triangle above, find the value of x.

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

4. If the two opposite interior angles are 45° and 85°, then the exterior angle is  .

5. 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 less than 90 degrees.

PQR2y3y130°

6. In the given triangle PQR, the exterior angle at Q is 130°. If the interior opposite angles are 2y and 3y, find the value of y and the measure of each interior angle.

7. The sum of an exterior angle and its adjacent interior angle is always 180°.

T

True

F

False