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Math for Kids23 chapters | 325 lessons

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Instructor:
*Dina Albert*

You come across so many shapes every day, and one of the most unique is the circle. This simple shape plays a huge role in our lives. In this lesson, you will learn about the parts of a circle!

On any given day, chances are you come in contact with a circle of some kind! You may notice how the bottoms of some bowls and plates are circles. The bottoms of soda cans are circles and wristwatches form a circle when they wrap around your wrist. Circles are everywhere and they are very special shapes.

Let's take a look at this plate. The red part of the plate is called the **circumference**, which measures the distance around the shape.

Whereas the entire red part of the plate is the circumference, any small section of the red part is called an **arc**.

One way to go through a circle is to draw a **chord**, which is a straight line that goes from one part of the circle to another. One special chord that goes through the center of a circle is called the **diameter**.

The **radius** is half the distance of the diameter. Both the diameter and radius can be drawn vertically, horizontally, and diagonally.

Last but not least, there is another line that touches the circle but is drawn outside of the circle. This line is called the **tangent**.

When two radii (the word for more than one radius) connect to an arc, the shape formed is called a **sector**. Sectors look just like the slices of pizza you see in that picture! The straight edges are the radii while the curved part (the crust) is the arc.

When a chord connects with an arc, the part formed is called a **segment**. Notice in the image how the strings of a guitar cross through the circle in the guitar. Each of the strings is a chord that creates different sized segments.

There are many properties of a circle. The three most important properties to remember are the **circumference** which is the distance around the shape, the **diameter** which is the distance from one end of the circle to the other crossing through the center, and the **radius** which is half of the diameter.

Also, remember that an **arc**, which is a small piece of the circumference, and a **chord**, which is a straight line that goes across the circle, connect together to make a **segment** while an **arc** and two **radii** form what is called a **sector** (like a pizza slice). Lastly, if you draw a line that is outside of the circle but still touching the circle, it is called the **tangent**.

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Math for Kids23 chapters | 325 lessons

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