Area of Rectangle

Area of rectangle is the region covered by the rectangle in a two-dimensional plane. A rectangle is a 2d shape which has four sides and four vertices. All the four angles of the rectangle are right angles. The opposite sides of the rectangle are equal and parallel to each other. To be noted, a parallelogram also has its opposite sides equal and parallel to each other but the angles are not equal to 90 degrees.

The surface area of a rectangle depends on its sides. Basically, the formula for area is equal to the product of length and breadth of the rectangle. Whereas when we speak about perimeter of a rectangle, it is equal to the sum of all its four sides. Hence, we can the region enclosed by the perimeter of rectangle is its area. But in case of square, since all the sides are equal, therefore, the area of square will be equal to square of side-length.

Area of rectangle = Length x Breadth

A = lb

Also, read:

Area Of Rectangle

Area of Rectangle Formula

The size of any object can be measured in many different ways. For instance, we all normally calculate how tall the building or the size of a swimming pool and how deep it is.

What is the area of a rectangular object, how to find out the area of the rectangle?

The area of a rectangle is calculated in units by multiplying the width (or breadth) by the Length of a rectangle. Lateral and total surface areas can be calculated only for three-dimensional figures. We cannot calculate for rectangle since it is a two-dimensional figure. Thus, the perimeter and the area of a rectangle is given by:

The formula for the Area of a Rectangle
The perimeter of a Rectangle P= 2(l + b)
Area of a Rectangle A = l × b

The area of any rectangle is calculated once its length and width are known. By multiplying length and breadth, the rectangle’s area will obtain in square-units dimension. In the case of a square, the area will become length2. The main difference between square and rectangle is that the length and breadth are equal for square.

How to Calculate the Area of a Rectangle

Follow the steps below to find the area:

Step 1:  Note down the dimensions of length and width from the given data.

Step 2: Multiply length and width values

Step 3: Write the answer in square units.

Below are some special formula related to the rectangle area.

  1. How to find the area with diagonal of rectangle and width

          Formula: Area = \(Width\ \sqrt{(Diagonal^2 – Width^2)}\)

  1. Find a missing side length when the area is known

           Formula: Length = Area/Width

Why Area of rectangle is length x breadth?

The diagonals of rectangle divides it into two equivalent right-angled triangles. Therefore, the area of rectangle will be equal to the sum of area of these two triangles.

Suppose, ABCD is a rectangle. 

Area of rectangle - Length x Breadth

Now, let diagonal AC divide the rectangle into two right triangles, i.e.∆ABC and ∆ADC.

So,

Area of rectangle ABCD = Area of ∆ABC + Area of ADC

Since, ABC and ADC are both equivalent triangles, therefore,

Area of ∆ABC = Area of ADC = ½ x base x height = ½ x b x h

Area (ABCD) = 2(½ x b x h)

Area (ABCD) = b x h

Since, base of triangles are equal to breadth of rectangle and height is the breadth of rectangle, therefore,

Area (ABCD) = Length x Breadth

Solved Examples

Example 1: Find the area of the rectangle whose length is 15 cm and the width is 4 cm?

Solution:

Given,

Length = 15 cm

Width = 4 cm

Area of a rectangle = Length × Width

15 × 4  = 60

So the area of rectangle = 60 cm2

Example 2: Find the area of a rectangular blackboard whose length and breadth are 120 cm and 100 cm respectively.

Solution:

Length of the blackboard = 120 cm = 1.2 m

Breadth of the blackboard = 100 cm = 1 m

Area of the blackboard = area of a rectangle = length x breadth = 1.2 m x 1 m = 1.2 square-metres

Example 3: The length of a rectangular screen is 15 cm. Its area is 180 sq. cm. Find its width.

Solution:

Area of the screen = 180 sq. cm.

Length of the screen = 15 cm

Area of a rectangle = length x width

So, width = area/length

Thus, width of the screen = 180/15 = 12 cm

Example 4: The length and breadth of a rectangular wall are 75 m and 32 m, respectively. Find the cost of painting the wall if the rate of painting is Rs 3 per sq. m.

Solution:

Length of the wall = 75 m

The breadth of the wall = 32 m

Area of the wall = length x breadth = 75 m x 32 m = 2400 sq. m

For 1 sq. m of painting costs Rs 3

Thus, for 2400 sq. m, the cost of painting the wall will be = 3 x 2400 = Rs 7200

Example 5: A floor whose length and width is 50 m and 40 m respectively needs to be covered by rectangular tiles. The dimension of each of the tile is 1 m x 2 m. Find the total number of tiles that would be required to fully cover the floor.

Solution:

Length of the floor = 50 m

The breadth of the floor = 40 m

Area of the floor = length x breadth = 50 m x 40 m = 2000 sq. m

Length of one tile = 2 m

The breadth of one tile = 1 m

Area of one tile = length x breadth = 2 m x 1 m = 2 sq. m

No. of tiles required = area of floor/area of a tile = 2000/2 = 1000 tiles

Frequently Asked Questions – FAQs

What is the formula for area of rectangle?

The formula for area of rectangle is:
Area = Length x Breadth

What is the perimeter of rectangle?

The perimeter of rectangle is sum of all its four sides. Hence,
Perimeter (rectangle) = 2 (Length + Breadth)

What is the area of rectangle?

The area of rectangle is the region occupied by the sides of rectangle.

Why area of rectangle is LB?

The area of rectangle is LB because we calculate here the square units of rectangle. After multiplying the total squares in the length and total squares in the width of the rectangle, will give the total squares in rectangle.

What is the unit of area?

The unit of area of any shape is square unit. For example, sq.m. or m^2.

Learn more about the rectangle, perimeter of a rectangle, quadrilaterals etc. by visiting our page BYJU’S.

1 Comment

  1. Very well written article

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