Question

The length of a rectangle is thrice its breadth. If the breadth is ‘b’ meters find the

expression for the following:

a) Area of the rectangle (1)

b) Perimeter of the rectangle (1)

c) If breadth is 3 cm, what is its perimeter?​

Answer 1

Answer:

breadth = b m

length = 3b m

a) Area of rectangle= l×b = b× 3b= 3b²

b) Perimeter of rectangle =2+(l×b)=2×( b+3b)=2×4b =8b

c)b=3 cm

Perimeter = 8×3=24m

Answer 2

Required Answer :-

• (a) The area of the rectangle = 3b² metre square.

• (b) The perimeter of the rectangle = 8b metres.

• (c) The perimeter of rectangle, if the breadth is 3cm is 24cm.

Step-by-step explanation:

To Find :-

• (a) Area of the rectangle.

• (b) Perimeter of the rectangle.

• (c) If breadth is 3 cm, what is its perimeter?

Solution:

Given that,

• The length of a rectangle is thrice its breadth. If the breadth is ‘b’ meters.

Assumption:

Let us assume the length of rectangle as (3b) metres, as the length of rectangle is thrice the breadth and given the breadth is (b) metres.

According the question,

• (a) Area of the rectangle

As we know that,

Area = ( length × breadth ) sq. units,

So,

⟶ Area = length × breadth

⟶ Area = [ 3b × b ] metre square

⟶ Area = [ 3b*b ] metre square

⟶ Area = 3b² metre square.

• (b) Perimeter of rectangle

As we know that,

Perimeter = 2 ( length + breadth ) units,

So,

⟶ Perimeter = 2 ( length + breadth )

⟶ Perimeter = 2 ( 3b + b ) ] m

⟶ Perimeter = [ 2 ( 4b ) ] m

⟶ Perimeter = [ 2*4b ] m

⟶ Perimeter = 8bm.

• (c) If breadth is 3 cm, what is its perimeter?

According the question,

As given, length is thrice it's breadth, So,

And given, Breadth = 3cm.

→ Length = ( 3b )cm = ( 3*3 )cm = 9cm.

As we know that,

Perimeter = 2 ( length + breadth ) units,

So,

⟶ Perimeter = [ 2 ( 9 + 3 ) ] cm

⟶ Perimeter = [ 2 ( 12 ) ] cm

⟶ Perimeter = [ 2*12 ] cm

⟶ Perimeter = 24cm.