Acute, Obtuse, and Right Triangles

Do you remember what triangles are? 🤔

All **triangles** have three sides and three angles.

An **angle** is the measure in degrees where **two sides meet**.

Triangles with different angles have different names.

The 3 angles in a **triangle **always **sum to 180°**.

But depending on how big and small each of these angles are, triangles can be named either **acute, obtuse, **or **right triangles**.

Let's learn each of these names:

In an **acute triangle**, all three angles are less than 90°.

**Tip:**** Acute angles **are angles less than 90°.

So it's easy to remember that acute triangles have only acute angles.😺

**Obtuse triangles** have one angle that's greater than 90°.

**Tip:**** Obtuse angles **are angles that are greater than 90°. So it makes sense that obtuse triangles have an obtuse angle!

**Right triangles **have one angle that's exactly 90°.

**Tip:** A right angle is marked with a small square where the lines meet.

Great job! 😀

Now let’s try to identify some triangles!

What kind of triangle is this? 👇

That’s right! 💪 This is an** obtuse** triangle! ✅

We know this is an obtuse triangle because one angle is **greater than 90°**.

Let’s try another one!

Is this triangle acute, obtuse, or a right triangle?

Great! 🎉 This is a right triangle!

A **right triangle** has one angle that measures 90°.

Let’s try one more!

Identify this triangle as acute, obtuse, or a right triangle.

Perfect! This is an **acute** triangle because all of its angles measure less than 90°.

Great job! 😀 Now, you know how to identify acute, right and obtuse triangles!

💪 Now, you can move on to the practice exercises!

Teachers:

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