Free Printable WorksheetMathGrade 8Math Curriculum7.G.B.5

8.127 Triangle Angle Sum and Exterior Angle Theorem Worksheet

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Worksheet Overview & Skills Covered

Core academic competencies and curriculum alignment

This Grade 8 Math worksheet provides structured practice on 8.127 Triangle Angle Sum and Exterior Angle Theorem. Students are guided through targeted exercises that build foundational understanding, computational accuracy, and critical thinking skills.

8.127 Triangle Angle Sum and Exterior Angle Theorem - Which unknown angle measure is correct using the triangle angle sum or exterior angle theorem? (CCSS 7.G.B.5; CA 7.G.B.5; MA 7.G.B.5)

Whether you are an educator preparing classroom handouts, a tutor reinforcing weekly topics, or a parent supporting homeschool learning, this printable resource gives students the deliberate practice required to achieve subject fluency and master state standards.

Grade

Grade 8

Subject

Math

Domain

Math Curriculum

Formats

PDF & DOCX

Sample Practice Problems

Preview the types of problems and questions covered in this worksheet

Below are sample questions representative of the exercises included on this worksheet and related 8.127 Triangle Angle Sum and Exterior Angle Theorem skill assessments:

Problem 1Difficulty: Hard
In triangle QRS, the exterior angle at S is 3 times angle R. If angle Q is 34 degrees, which choice is angle R?
A15 degrees
B17 degrees
C19 degrees
D21 degrees
Solution & Explanation:The exterior angle at S equals the sum of the two remote interior angles, so 3(angle R) = angle Q + angle R. This gives 3R = 34 + R, so 2R = 34 and angle R = 17 degrees.
Problem 2Difficulty: Hard
In triangle NOP, angle O is 7 degrees less than angle N, and angle P is 11 degrees more than angle O. What is angle P?
Solution & Explanation:Let angle N = x. Then angle O = x - 7 and angle P = x + 4. Use the triangle angle sum: x + (x - 7) + (x + 4) = 180. This simplifies to 3x - 3 = 180, so x = 61. Therefore angle P = 65 degrees.
Problem 3Difficulty: Hard
Triangle ADX has angle A = x + 12 degrees, angle D = x + 18 degrees, and an exterior angle at X of 4x - 30 degrees. Which choice is angle X?
A84 degrees
B86 degrees
C88 degrees
D90 degrees
Solution & Explanation:Set the exterior angle equal to the sum of the remote interior angles: 4x - 30 = (x + 12) + (x + 18). This gives x = 30. The exterior angle is 90 degrees, so angle X = 180 - 90 = 90 degrees.

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Frequently Asked Questions

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QWhat grade level and standards does this worksheet align with?

This worksheet is designed specifically for Grade 8 Math students. It aligns with educational standard 7.G.B.5 (Primary standard selected for prompt fields: CCSS 7.G.B.5. Skill statement: Which unknown angle measure is correct using the triangle angle sum or exterior angle theorem? Associated standards listed with this skill: CCSS 7.G.B.5; CA 7.G.B.5; MA 7.G.B.5. Use this embedded wording as the best available supporting standard description for this workflow.).

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