8th Grade Angles in Triangles and Parallel Lines Test with Point Values (PDF)

8th Grade math test: Angles in Triangles and Parallel Lines – Maths PDF

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This grade 8 angle relationships test for 8th Grade covers angles in triangles and parallel lines (Common Core 8.G.A.5), with a free PDF to print.

This 20-point test checks angle relationships in triangles and with parallel lines cut by a transversal (Common Core 8.G.A.5). Work alone, show every step, and write each final answer clearly. You have 45 minutes. Calculators are not needed unless a question says so.

Time and points

About this test

Grade: Grade 8
Chapter: Angles in Triangles and Parallel Lines
Standards: 8.G.A.5
Time: 45 minutes
Total: 20 points

Grade 8 angle relationships test: questions

Question 1 – Triangle angles [3 pts]

Find x. Not drawn to scale.

Find the third angle of the triangle and the exterior angle at the right vertex.

Question 2 – Solve for x [3 pts]

The angles of a triangle are \(x\), \(2x + 15\) and \(3x – 15\) degrees. Find \(x\) and the three angles.

Question 3 – Parallel lines [3 pts]

Lines j and k are parallel.

Lines j and k are parallel. Find the angle marked x and explain how you know.

Question 4 – Equation with angles [3 pts]

Lines j and k are parallel.

Lines \(j\) and \(k\) are parallel. Find \(x\).

Question 5 – Similar triangles [3 pts]

Triangle 1 has angles \(35^{\circ}\) and \(90^{\circ}\). Triangle 2 has angles \(90^{\circ}\) and \(55^{\circ}\). Are they similar? Explain.

Question 6 – Exterior angle [2 pts]

An exterior angle of a triangle is \(118^{\circ}\). One remote interior angle is \(49^{\circ}\). Find the other remote interior angle.

Question 7 – Linear pair [1 pt]

Two angles form a linear pair. One is \(20^{\circ}\) less than three times the other. Find both angles.

Question 8 – Explain [2 pts]

A student says a triangle can have two right angles. Explain why this is impossible.

Key facts behind this grade 8 angle relationships test

Key facts

Angles of a triangle: \(a + b + c = 180^{\circ}\).
Exterior angle = sum of the two remote interior angles.
Parallel lines: corresponding and alternate interior angles are equal.
Co-interior angles add to \(180^{\circ}\); vertical angles are equal.
Two equal angles are enough to show two triangles are similar (AA).

How to use this grade 8 angle relationships test

Time yourself: the test is designed for an average student in 45 minutes. Answer the questions you are sure of first, then come back to the longer ones and check your units.

All Grade 8 chapters: Grade 8 math.

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