What is a Circle?
You see different shapes in your daily life. Do you know what is the shape of a ring, or a coin, or that of the sun and the moon? Yes! It is a circle. A circle is a round shape. All points present on its boundary, a curved line, are placed at an equal distance from its centre. It is a two-dimensional shape. In your day-to-day life, you must have come across several objects that are in the shape of a circle.
For example, a ball, a dish, a clock, a doughnut, etc. Check the image below to know some objects that are in the shape of a circle.
Shape of a Circle
In the following sections, we will learn more about circles and their properties in detail.
Parts of Circle
The parts of a circle are shown in the below picture.
Parts of a Circle
Radius: A radius of a circle is a line drawn from the centre of the circle to any point on the circle edge. Letter ‘R’ is generally used to show the radius of the circle.
Circumference: Circumference of the circle is defined as the boundary of the circle. We can say that the measure of the boundary of the circle is called the circumference.
Chord: In a circle, a chord is a line segment that joins any two points on the circumference of the circle. It divides the circle into two parts. These parts are known as the segments of the circle.
Diameter: It is a line segment that passes through the centre of the circle. The endpoints of the diameter lie on the circumference of a circle. The diameter of a circle is double the length of the radius. It is generally represented by the letter ‘D’. Hence 2R=D.
Sector: A sector of a circle is the region formed by two of its radii and the arc in between. An angle is subtended at the centre of the circle by a sector.
Segment: A segment of a circle is the area that is bounded by an arc and a chord of the circle. There are two types of segments- minor and major. A segment that is made by a minor arc is called a minor segment and a segment that is made by a major arc is called a major segment.
Arc: The arc of a circle is a part of its circumference.
Tangent: In a circle, a tangent is a straight line that passes by touching the circumference of the circle only at one point. It is important to remember that it does not pass through the circle. The tangent meets the radius of the circle at an angle of 90o.
Conclusion
In the initial phase of introducing the concept of a circle to students, it is required to teach them the definitions of the parts of a circle. The definitions and concepts discussed above will be of great help for students learning about circles for the first time.
FAQs on Circles for Kids - Definitions and Properties
1. What is a simple definition of a circle for kids?
A circle is a perfectly round shape made from a single curved line. Every point on this line is the exact same distance from a special point right in the middle, called the centre. Unlike a square or triangle, it has no corners or straight sides.
2. What are some common examples of circles in our daily life?
You can find circles everywhere you look! Some common examples include:
- The face of a wall clock
- A car tyre or a bicycle wheel
- A full pizza or a dinner plate
- The top of a coin
- A hula hoop or a bangle
3. What are the basic properties of a circle that make it special?
A circle has a few simple but important properties:
- It is a closed curve, meaning it has no start or end point.
- It has no corners or vertices.
- It has no straight sides or edges.
- All points on its outer boundary are an equal distance from its centre point.
4. How is a circle different from an oval?
A circle is different from an oval because of its perfect symmetry. In a circle, the distance from the centre to any point on its edge is always the same. An oval is also a closed curve, but it is stretched out like a squashed circle. This means the distance from its centre to its edge changes depending on where you measure.
5. Why are wheels on cars and bicycles always circular?
Wheels are circular because this shape allows for smooth and efficient rolling. Since every point on the edge of a circle is the same distance from its centre (the axle), the vehicle stays at a steady height as the wheel turns. If a wheel were a square or triangle, the ride would be extremely bumpy and difficult.
6. Does a circle have any corners or straight edges?
No, a circle does not have any corners or straight edges. Its boundary is a single, continuous curved line. This is the main feature that makes it different from polygons like squares, rectangles, and triangles, which are all made of straight lines that meet at corners.
7. What is the most important rule that a shape must follow to be a perfect circle?
The single most important rule is that every point on the boundary of the shape must be exactly the same distance from its centre. This special, constant distance is a key property of a circle. If even one point is slightly closer to or farther from the centre than the others, the shape is no longer a perfect circle.
