### Equilateral Triangle

#### Lesson Objective

In this lesson, we will learn about equilateral triangles...

#### About This Lesson

In this lesson, we will:

- learn what are equilateral triangles
- see some examples on identifying them.

This lesson shows you the concepts that you should know about a line that is parallel to the x-axis or y-axis of the coordinate plane. Also, we will see some examples on determining its equation.

The study tips below will give you a short summary on this.

The math video below will explain in depth about this. Furthermore, it will show some examples so that you can understand this lesson better.

### Study Tips

#### Tip #1

When a triangle has three sides (edges) of equal length, this triangle can be called an equilateral triangle. See some examples below:

#### Tip #2

Since this type of triangle has three sides of equal length, each of its internal angles is 60^{°}. See the picture below:

The math video below will explain more...

### Math Video

#### Lesson Video

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#### Math Video Transcript

00:00:03.140

In this lesson, we will learn about equi. triangle.

00:00:08.230

A triangle is an equi. triangle, when all the sides of the triangle, have the same length.

00:00:16.030

Now, to demonstrate this, let's move vertex 'B' to the right.

00:00:22.150

Here, we can see that when all the 3 sides have the same length, we get an equi. triangle.

00:00:32.020

Also, it is important to note that, each of its internal angles is equal to 60 degrees.

00:00:40.130

Let's see some examples.

00:00:44.010

Is this an equi. triangle?

00:00:48.030

Since this triangle has 3 sides of equal length, this is an equi. triangle.

00:00:55.170

Next example, how about this triangle?

00:01:02.020

We can see that, all these angles are 60 degrees.

00:01:07.070

This means that, these 3 sides must have the same length.

00:01:12.140

Hence, this is an equi. triangle.

00:01:17.130

Last example, now, only these 2 sides have the same length.

00:01:25.130

Therefore, this is not an equi. triangle.

00:01:30.160

That is all for this lesson.

### Practice Questions & More

#### Multiple Choice Questions (MCQ)

Now, let's try some MCQ questions to understand this lesson better.

You can start by going through the series of questions on equilateral triangles or pick your choice of question below.

#### Site-Search and Q&A Library

Please feel free to visit the Q&A Library. You can read the Q&As listed in any of the available categories such as Algebra, Graphs, Exponents and more. Also, you can submit math question, share or give comments there.