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Introduction 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 supplementary angle of the given

In the same way that alternating squares on a chess board are the same color, alternating angles are equal.
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CALCULATOR

## Transversals, Parallel Lines & Angles Calculator

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

## Finding Angles between a Transversal & Parallel Lines

When a transversal crosses parallel lines, we can imagine the intersection as a chess board and use the colors to figure out all the angles using just one given angle. We start by figuring out which angles are equal to the given angle. To do this, we just need to see which ones fall on the same chess board color as the given angle.
PRACTICE
Finding Angles between a Transversal & Parallel Lines

## Practice: Finding Angles Between a Transversal & Parallel Lines

Question 1 of 8: Find the unknown angle below ⬇️:

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

Tap/click on the angle we know:

CONCLUSION
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