Sectors of a Circle

What are Sectors of a Circle?

The sectors of a circle are parts or portions of the circle that are bounded by two radii and the corresponding arc between them.

What is a Central Angle in a Circle Sector?

A central angle is an angle with its vertex at the centre of a circle and its sides extending to the endpoints of an arc. It determines the size of the sector and is measured in degrees or radians.

How is Area of a Sector of a Circle Calculated? 

The area of a sector can be calculated using the formula as follows:

Area of Sector = (θ/360) × πr2

Where, 

  • θ is the measure of the central angle in degrees, 
  • π is a mathematical constant (π≈3.14), and 
  • r is the radius of the circle.

What is Arc Length of a Sector?

The arc length of a sector is the distance along the circumference of the circle that forms the arc. 

What is the formula for Arc length of a Sector?

Arc length of a sector is given by the following formula:

Arc Length of Sector = (θ/360) × 2πr

Where, 

  • θ is the measure of the central angle in degrees, 
  • π is a mathematical constant (π≈3.14), and 
  • r is the radius of the circle.

How is Perimeter of a Circle’s Sector Calculated?

The perimeter of a circle sector is the sum of the length of the arc and the lengths of the two radii that form the sector. The formula for the perimeter of a circle is given by: 

  • Perimeter of Sector = Arc Length + 2 × r
  • Perimeter of Sector = (θ/360) × 2πr + 2 × r

Where, 

  • θ is the measure of the central angle in degrees, 
  • π is a mathematical constant (π≈3.14), and 
  • r is the radius of the circle.

Can Area of Sector be Larger than Area of Whole Circle?

No, the area of any sector can’t be larger than the area of the whole circle as it is the part of the circle and it can maximum be equal to the area of a circle as the largest possible sector is a full circle.



Sector of a Circle

Sector of a Circle is one of the components of a circle like a segment which students learn in their academic years as it is one of the important geometric shapes. The sector of a circle is a section of a circle formed by the arc and its two radii and it is produced when a section of the circle’s circumference and two radii meet at both extremities of the arc. From a slice of pizza to a region between two fan blades, we can see sectors of the circle in our daily lives everywhere.

In this article, we will explore the geometric shape of the sector which is derived from the circle in detail including its areas, perimeter, and all the formulas related to the sector of a circle.

Table of Content

  • What is Sector of a Circle?
    • Sector of a Circle Definition
    • Sector Angle
  • Sector of a Circle Examples
  • Sector of a Circle Area
  • Formula for Area of a Sector
  • Derivation of Formula for Area of a Sector
  • Area of Minor Sector 
  • Area of Major Sector 
  • Arc Length of Sector of a Circle
  • Formula for Arc Length of a Sector
  • Derivation of Formula for Arc Length of a Sector
  • Sector of a Circle Perimeter
  • Perimeter of a Sector Formula
  • Sample Problems Sector of a Circle
  • Summarizing Important Formulas of Sector of a Circle

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What is Sector of a Circle?

A sector is a segment of a circle that includes an arc and the two radii that connect the arc’s endpoints to the circle’s centre. It represents a fraction of the circle, defined by the arc—part of the circle’s perimeter—and the radii at the arc’s ends. Visually, a sector resembles a piece of pizza or pie, highlighting its nature as a portion of the whole circle....

Sector of a Circle Examples

Some examples of sectors of circles are slices of pizza or pie, a clock face, a fan blade etc. Some examples of sectors of the circle are shown in the following illustration:...

Sector of a Circle Area

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Formula for Area of a Sector

Formula for the area of a sector is given as follows:...

Derivation of Formula for Area of a Sector

Consider a circle with centre O and radius r, suppose OAPB is its sector and θ (in degrees) is the angle subtended by the arcs at the centre....

Area of Minor Sector

The formula derived in the above section is generally used as the area of the minor sector. As θ is mostly the general representation of the angle of the minor sector. Thus...

Area of Major Sector

As sector angle for the major sector is generally represented by 360° – θ. Thus, the area of the major sector is given by...

Arc Length of Sector of a Circle

The arc length of a sector is the length of the arc that is enclosed by the sector. In other words, an arc is the sub-length of the circumference of the circle. It is a general belief that arc length is the perimeter of the sector but it is only the circular part of the sector not the complete perimeter. We will discuss the perimeter in the article ahead....

Formula for Arc Length of a Sector

The formula for the arc length of a sector with θ sector angle is given as follows:...

Derivation of Formula for Arc Length of a Sector

Consider a circle with centre O and radius r. Let OAPB be a sector of the circle, and θ° be the angle subtended by the arc at the centre O....

Sector of a Circle Perimeter

The perimeter of any geometric shape is its boundary. Thus, for the sector of a circle perimeter is also the boundary of the circle which include the arc length as well as the radius of the circle which encloses the sector....

Perimeter of a Sector Formula

The formula for the perimeter of a circle is given by:...

Summary – Sector of a Circle

Sector is the region enclosed by two radii and arc length in the circle. Angle subtended by the arc on the centre is known as the central angle.Area of a sector of the circle is Arc length of the sector of the circle is Perimeter of the sector of the circle is...

Sample Problems Sector of a Circle

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Summarizing Important Formulas of Sector of a Circle

Formula for Area of a Sector: A = (θ/360°) × πr2 Formula for Arc Length of a Sector: Arc Length = θ°/360° × 2πrFormula for Perimeter of Sector of a Circle: P = (θ/360) × 2πr + 2 × r...

Sectors of a Circle – FAQs

What are Sectors of a Circle?...