Angles

In the last lesson, you learned about lines, line segments and rays.

They're all around us.

Look around and you'll start to notice lots of places where **two line segments ****cross** or **meet**** **each other at a point.

In geometry, when two lines, line segments, or rays meet each other, they make an **angle**.

In this lesson, let's learn more about angles! 🤗

🤓 Look at these two rays.

These rays are sitting on top of each other, and have a **common endpoint X.**

Now, let's hold one ray at its place, and **turn the other ray **towards the left, around X.

✅ Now, the rays **have a common endpoint and a turn **in between them.

👉 This turn is called the **angle **between these two rays.

Theamount of turnbetween two lines, line segments or rays around a common point is called theanglebetween them.

- The two lines that form the angle are called the **arms.**

- The common point at which these lines meet is called the **vertex.**

**Remember:**

Angles exist between any two crossing or meeting lines.

😎 Let's look at our two overlapping rays again.

Like before, let's hold one ray at its place, and **turn the other ray **towards the left.

Can you tell what will happen if we turn this ray **all the way around**?

You're right! 😃

👉 The ray will **trace a circle,** and come back to its original place.

To measure angles, we divide this circle** **into **360 equal parts**. Each part is called **1 degree (written as 1°).**

🤓 So, two lines can have up to a **360° angle **between them.

A90°angle is called aright angle.

A right angle is marked by **drawing a square **at the vertex.

👉 For example, windows and books have right angles.

An angle that's less than 90° is called anacute angle.

15°, 30°, 45° and 60° are all acute angles.

👉 For example, pizza slices and party hats have acute angles.

An angle that is greater than 90° but less than 180° is called anobtuse angle.

95°, 120°, 150° and 175° are all obtuse angles.

👉 For example, roofs of houses and parts of beehives have obtuse angles.

Congratulations! 🤗 You now know what angles are!

Now go ahead and try practice. 💪

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