Triangle Sum Theorem Worksheet

Practice problems for 7th graders on the Triangle Sum Theorem, including finding missing angles and applying the theorem to various triangles.

Grade 7 Math GeometryTriangle Sum Theorem

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Includes

Fill in the Blanks2 Short AnswerMultiple ChoiceTrue / False

Standards

CCSS.MATH.CONTENT.7.G.A.2CCSS.MATH.CONTENT.7.G.A.5

Topics

mathgeometrytrianglesanglesgrade 7

7 sections · Free to use · Printable

Triangle Sum Theorem

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Read each question carefully and use the Triangle Sum Theorem to find the missing angle measures. Show all your work.

1. The sum of the interior angles of any triangle is always equal to degrees.

2. If you know two angles of a triangle, you can find the third angle by their sum from 180 degrees.

3. Find the measure of the missing angle in the triangle below:

4. A triangle has angles measuring 35° and 85°. What is the measure of the third angle?

5. Which of the following sets of angles could form a triangle?

45°, 45°, 95°

60°, 60°, 60°

30°, 50°, 100°

All of the above

6. An isosceles triangle has two angles that measure 50° each. What is the measure of the third angle?

50°

80°

100°

130°

7. A triangle can have two obtuse angles.

True

False

8. An equilateral triangle has three angles that each measure 60°.

True

False

9. In a right-angled triangle, one of the acute angles measures 40°. What is the measure of the other acute angle? Explain your reasoning.