QUICK LINKS


Introduction

QUICK LINKS


Introduction

Transversals, Parallel Lines, and Angles

INTRO
A transversal is a line that crosses two or more lines. When the lines crossed by a transversal are parallel, we can figure out the values of all the angles formed with just one given angle.
To do this, we like to imagine the set of lines as a chess board so that the colors can help us identify which angles are equal.

angles equal to the given angle

angles equal to the supplementary angle of the given

In the same way that alternating squares on a chess board are the same color, alternating angles are equal.
Check out our
Calculator
or explore our
Lesson
and
Practice
sections to learn more about how to find the angles between a transversal and parellel lines and test your understanding.

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We have some questions for you! Help us out through this
CALCULATOR

Transversals, Parallel Lines & Angles Calculator

Which set of lines best matches the ones in your question?

Step 1. Imagine the diagram as a chess board & identify a given angle.

Click or tap on an angle that you already know. You might know more than one, but we only need one to get started.

Step 2. Identify all the angles that are equal to the given angle.

Equal angles make a “zig zag” along the same square color. So, all the purple angles are .
If you've found the unknown angle, stop 🛑. If not, keep going.

Step 3. Find the supplementary angle of the given angle.

Since we still haven't found the unknown, we can use supplementary angles to find the angle right next to our given.
So, the green angle is .
If you've found the unknown angle, stop 🛑. If not, keep going.

Step 4. Identify all the angles that are equal to the supplementary angle.

Equal angles make a “zig zag” along the same square color. This gets us the rest of the angle values.
So, if the unknown angle is purple, it is . If the unknown angle is green, it is .
KEY STEPS

How to find Angles between a Transversal & Parallel Lines

Step 1. Imagine the diagram as a chess board & identify a given angle.

You might be given more than one, but only one is needed to get started.

Step 2. Identify all the angles that are equal to the given angle.

Equal angles make a “zig zag” along the same square color.
If you've found the unknown angle, stop 🛑. If not, keep going.

Step 3. Find the supplementary angle of the given angle.

If you've found the unknown angle, stop 🛑. If not, keep going.

Step 4. Identify all the angles that are equal to the supplementary angle.

Equal angles make a “zig zag” along the same square color.
LESSON
Finding Angles between a Transversal & Parallel Lines
PRACTICE
Finding Angles between a Transversal & Parallel Lines
CONCLUSION
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