# CLASS-4PERIMETER OF A RECTANGLE

PERIMETER OF A RECTANGLE -

As we all know that, a rectangle is a four sided figure, and Its opposite sides are equal.

The longer side is known as length and the shorter side is known as breadth/ width.

Perimeter of a rectangle = (length + breadth) x 2

Example.1) Find the perimeter of a rectangle whose length is 1.85 cm and breadth is 2.20 cm.

Ans.)

Length = 1.85 cm

∴ Perimeter of a rectangle=

= (length + breadth) x 2

= (1.85 cm + 2.20 cm) x 2

= 4.05 cm x 2

= 8.10 cm

Ans:The perimeter of the rectangle is 8.10 cm.       (Ans.)

Example.2) The perimeter of a rectangle is 60 m. Find the breadth of the field if its length is 18 m.

And.) Perimeter of the rectangle 60 m, and length is 18 m

As we know that, perimeter of the rectangle = 2 (Length + Breadth)

So, 60 = 2 (Length + Breadth)

=>   (Length + Breadth) = 30

=>   18 + Breadth = 30

=>   Breadth = 30 - 18 = 12

So, the required breadth is 12 m    (Ans.)

Example.3) If the length of the rectangular garden is thrice its breadth and if the breadth is 15 m find the perimeter of the garden

Ans.) Let, Length = L, and Breadth = B

As per the given condition, length of the rectangular garden is thrice its breadth, so L = 3 B and B = 15 m

Now, perimeter of rectangle is = 2 (Length + Breadth)

= 2 (L + B)

= 2 (3 B + B)   [where L = 3 B]

= (2 X 4 B)

=  8 B

=  (8 X 15)     [where B = 15 m]

= 120 m

Now, as per the condition -

Perimeter of Rectangle is = 2 (Length + Breadth)

So,         120 m = 2 (Length + Breadth)

Length + Breadth = 60 m

Now,     Length + 15 m = 60 m

so,        Length = 60 m - 15 m = 45 m

Or,

L = 3 B = (3 X 15)

L = 45 m

So, the length and perimeter of the rectangle is 45 m and 120 m respectively.    (Ans.)