Common Core Math Vocabulary

Circle - Definition with Examples

let's learn Let's learn!

What is a circle? 
A circle is a round shaped figure that has no corners or edges. 

In geometry, a circle can be defined as a closed, two-dimensional curved shape.

circle shape

We can find the shape of a circle in a car tire, wall clock and a lollipop, around us. 

circle real life example around us
 
Center of a Circle
The center of a circle is the center point in a circle, from which all the distances to the points on the circle are equal. 

Here, point P is the center of the circle.

center of the circle center point
 
Semicircle:
A semi-circle is half of a circle, formed by cutting a whole circle along a line segment passing through the center of the circle.
semicircle or half circle
 
Quarter Circle:
A quarter circle is a quarter of a circle, formed by splitting a splitting a circle into 4 equal parts or a semicircle into 2 equal parts. 

A quarter circle is also called a quadrant. 

Quarter of a circle or Quadrant

  Fun Facts

  •  
  • A straight line is a circle with an infinite area.
  • A circle can have infinite lines of symmetry.
  • The word ‘encyclopedia’ literally means ‘the circle of learning’.
  • A circle can be divided equally irrespective of its size. 
 

let's sing Let's sing!

The tires of an old yellow car.
The round lid of a candy jar.
The clock hanging on the wall.
A cat playing with the red ball.
The sweet chocolate donut I ate,
And a whole apple pie on my plate. 
The shiny buttons on my dress.
What’s the shape? Take a guess.
They are all round like a C-I-R-C-L-E.
 

let's do it Let's do it!

Instead of handing out geometry worksheets to your children, ask your child to observe/spot the things that are circular in shape, such as a bangle, a door knob, or a hula hoop. 
You can also ask your child to pick out a circular object such as Bangle, or a Hula hoop and show/identify the center of the circle in it. Ask them to show you how a semi-circle or a quarter circle can be formed. 
 

related math vocabulary Related math vocabulary

Sphere, Area, Perimeter.

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