Rectangle Definition

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A rectangle in Euclidian geometry was put forward around 300 B.C. In plane geometry, the rectangle was held to be simply a quadrilateral having 4 right angles. Previously, it was also known as an equiangular quadrilateral. The present terminology is derived from the Latin word ‘rectangulus’ which can be divided into the components of ‘angulus’ which means angle and ‘rectus’ which means right. 

Read on to know more about the definition of Rectangle and its other dimensions. 


Rectangle Definition 

In geometry, rectangle comprises of a 2D shape having four vertices and four sides and each angle measures 90°. It means that two sides always meet at right angles in a rectangle.


Moreover, sides facing each other are of the same lengths as well as parallel; that is, the distance between those two sides always remain the same at any given point. From rectangle definition, these characteristics are evident in the figure indicated below. 

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Owing to the existence of parallel sides in a rectangle, it is termed as a parallelogram. Furthermore, it can also be an equiangular quadrilateral, given that all of its angles are equal.


Did you know? 

All squares are rectangles, but not all rectangles are squares. Also, even though all parallelograms may not be rectangles but all rectangles are necessarily parallelograms. Interesting isn't it!


Formula of Rectangle 

To define the area of a rectangle, its length and breadth are taken into consideration. It is the product of adjacent sides of a rectangle, that is, the product of its length and breadth. Hence, the area of a rectangle is,


A = (l X b) sq. units


[Where,

A = area of rectangle 

l = length of rectangle 

b = breadth of rectangle]

Similarly, the perimeter of a rectangle is the sum of its four sides. Therefore, the perimeter of a rectangle is,

P = 2 X (l + b) units


[Where,

P = perimeter of rectangle 

l = length of rectangle 

b = breadth of rectangle]

The formula reflects that as the opposite sides of a rectangle are parallel, the rectangle’s perimeter would be two times the sum of length and breadth. 


Properties of Rectangle 

Proceeding from the rectangle definition, its main properties are – 

  • All the angles are right-angled.

  • Opposite sides of a rectangle are congruent as well as parallel.

  • There is congruency in opposite angles which are created when two diagonals bisect.

  • Diagonals of a rectangle bisect each other, i.e., both are divided equally and congruent as well.

  • A rectangle is held to be a special instance of parallelogram comprising of right angles.

Solved Example 

Here is an example, for better understanding of the definition of a rectangle –

  • What is the area and perimeter of a rectangle where the length and breadth are 15 cm and 11 cm respectively?

Given, length = 15 cm, breadth = 11 cm

Area of rectangle = (length × breadth) cm2 = (15 X 11) cm2 = 165 cm2

Perimeter of rectangle = 2 (length + breadth) = 2 (15 + 11) cm = 52 cm

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FAQ (Frequently Asked Questions)

1. What are Rectangle Definition and Formula?

Ans. Rectangle definition is understood as a 2D shape with 4 straight sides. All the interior angles of a rectangle are at right angles, i.e., 90 degrees. Moreover, opposite sides of a rectangle are equal in length and parallel to each other. Note that a square amount to one type of rectangle. 


The formula of a rectangle is in terms of its area and perimeter. The area is, A = length X breadth and the perimeter is, P = 2 X (length + breadth). 

2. How to Define an Area of a Rectangle?

Ans. The area of a rectangle definition is that it is the product of length and breadth. Its formula is represented as A = l x b, where l stands for length and b stands for breadth. 


For example, let a rectangle's breadth be 25 metres, and the length is 35 metres, then the area of such rectangle is, 35 metres X 25 metres which are 875 sq. metres.

3. What are the Major Properties of a Rectangle?

Ans. From the rectangle definition, properties of a rectangle may be derived. Some major properties are – (1) congruency of opposite sides, bisection of diagonals and parallel sides, (2) angles of a rectangle are right angles, and (3) diagonals are also congruent.