Parts of a Circle

In this page we are going to discuss about parts of a circle concept. Circle is defined as the set of points that is at an equal distant from the centre of the circle. The circle is symbolically represented as . The circle can drawn by a complete revolution of 360° from a single point called the centre without changing the radius.

There are a number of parts of the circle like diameter, radius and chords of a circle as shown in the above figure.

Listed below are some of the parts of a circle.

• Radius: It is one of the parts of the circle that is defined as the distance between the center of the circle and a point on the circle. It is denoted as the r.

• Diameter: It is one of the parts of the circle that is defined as the distance between two point on the circle which passes through the center of the circle. Its symbol is d. It is also called the longest chord, but not every chord is a diameter. The diameter is twice the times of radius in the circle.

D = 2r or r =(½) d

• Chord: It is one of the parts of the circle that be defined as the line whose end points are on the circle.

• Secant Line: It is defined as the line that intersects the circle exactly at two points.

• Tangent Line: It is defined as the line that intersects the circle on the point.

The relation between a diameter and a chord can be any one of the following:

• Chord and Diameter can be perpendicular to each other
• Chord and Diameter can be parallel to each other.
• Chord and Diameter can intersect each other.
• Chord and Diameter can overlap each other.

Chord:

A line segment which joins the two ends of a circle or a curve is known as a chord. It is represented as shown below

Arc:

An arc is any portion of a circumference of a circle. It is as shown in the figure below

Relation of Chord as a diameter:

A diameter is the distance between any two points that passes through the centre of the circle.

In the above figure, the diameter and chord are perpendicular to each other.

In the above figure, the diameter and chord are parallel to each other.

In the above figure, the diameter and chord intersect each other at e.

In the above figure, the diameter and chord overlap each other.

Below are some examples on parts of circle

Example 1:

Find out the each statement is true or false by using this following diagram.

a. The line OD is radius.

Answer: True

Explanation: The line OD seems the distance between the center and point on the circle.

b. The line CB is a diameter.

Answer: False

Explanation: The line CB is a chord, because its ly between the point on the circle.

C. The line CD is the diameter.

Answer: True

Explanation: The line CD is the distance between the two points on the circle cross through the center of the circle.

Example 2:

Find the diameter of the circle whose radius is 4 cm.

Solution:

d = 2r

d = 2*r = 2*4 = 8 cm.