Acute Triangle

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Lesson Objective

In this lesson, we will learn about acute triangles.

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About This Lesson

In this lesson, we will:

  • Learn what are acute triangles.
  • See some examples on identifying them.

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.

acute triangle

Study Tips

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Tip #1

All the internal angles of a triangle must be less than 90° for it to be an acute triangle. See the picture below:

acute triangle with all internal angles less than 90 degrees
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Tip #2

Here are some examples of:

examples on acute triangles
examples of not acute triangles

The math video below will explain more...

Math Video

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Lesson Video

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Math Video Transcript

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

For a triangle to be an acu. triangle, all the internal angles, must be less than 90 degrees.

Now, let's move this vertex, and see what happens..

Notice that, when this angle becomes 90 degrees, this triangle, is not an acu. triangle.

Next, as we continue to move this vertex, this angle is now greater than 90 degrees.

Hence, this triangle is not an acu. triangle.

Let's see some examples.

Is this an acu. triangle?

Since all the internal angles are less than 90 degrees, this is an acu. triangle.

How about this triangle?

Now, observe that, this angle is 90 degrees.

Since this angle is not less than 90 degrees, it is not an acu. triangle.

Last example, is this an acu. triangle?

Notice that, this angle is 110 degrees, which is greater than 90 degrees.

Therefore, this is not an acu. triangle.

That is all for this lesson.

Practice Questions & More

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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 acute triangles or pick your choice of question below.

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