Circle and Related Terms


 
 
Concept Explanation
 

Circle And Related Terms

Circles:

A collection of all points in a plane which are at a fixed distance from a fixed point is known as a circle. or we can say that a circle is a path followed by a point which is moving on a plane such that its distance from the fixed point remains the same. Circle is a set of points or collection of points in a plane which are equidistant from a fixed point..

The various terms used in context with circle are

1. Center: The fixed point from which the distance remains the same is called the center of the circle. In the figure O is the centre of the circle.

2. Radius: The fixed distance from the center is called radius of the circle. It is also defined as the line segment joining the center to any point on the circle. In the figure ON is the radius of the circle.The plural of radius is radii

3. Position of a point with respect to a circle:  A circle divides the plane into three parts.

(1)  Inside the circle or interior of the circle: A point is said to be inside the circle if its distance from the center is less than the circle. All points lying inside the circle constitute interior of a circle.

(2) On the Circle: A point is said to lie on the circle if its distance from the center is equal to the radius of the circle.

(3) Outside the circle or exterior of the circle: A point is said to be outside the circle if its distance from the center is more than the circle. All points lying outside the circle constitute exterior of a circle.

Circular Region:

The collection of points lying inside and on the circle are called its circular region. It is collection of all points whose distance the center is either equal to radius or less than the radius. It is also called Circular Disc.

Concentric Circles:

Circles having same center point but different radii are known as concentric circles.

Sample Questions
(More Questions for each concept available in Login)
Question : 1

Which of the following statement / statements are correct regarding the figure below

(1) Point P, R and S lie on the circle

(2) O is the centre of circle.

(3) Point E, F and C lie in the interior of the circle.

(4) Point A, B, G and D lie in the exterior of the circle.

Right Option : D
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Question : 2

Which of the following statement / statements are not correct regarding the figure below

(1) Point A, B, C, D and E lie on the circle

(2) OC, OA and OB are the radii of the circle.

(3) Point P lies in the interior of the circle.

(4) Point Q lies in the exterior of the circle.

Right Option : D
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Explanation
Question : 3

Which of the following statement / statements are correct regarding the figure below

(1) Point A, B, C, D and E lie on the circle

(2) OC, OA and OB are the radii of the circle.

(3) Point P lies in the interior of the circle.

(4) Point Q lies in the exterior of the circle.

Right Option : D
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Explanation
 
 


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