Question

The length of a rectangle is three times its breadth .What is the length ,if the perimeter is 40 cm?

Answer 1

Answer:

Let l and b be the length and breadth of rectangle

Given that, l=3b

We know that,

Perimeter of the rectangle =2×(l+b)

⇒40 cm=2×(3b+b)=2×4 b=8 b

⇒b=

8

40

cm=5 cm

⇒l=3b=3×5 cm=15 cm.

Hence, the length and width of the rectangle are 15 cm and 5 cm% respectively.

Answer 2

Given :

• The length of a rectangle is three times its breadth
• Perimeter = 40 cm

To find :

• What is the length

Solution :

Let l and b be the length and breadth of rectangle

Now ,

Question says that

l = 3b

Perimeter of Rectangle = 2 × ( l + b )

$\;\;\bf{\;\;\red{⟹ 40 cm = 2 × ( 3b + b ) = 2 × 4b = 8b}}$

$\;\;\bf{\;\;\blue{⟹B = \frac{40}{8}cm = 5cm }}$

$\;\;\bf{\;\;\green{⟹ l = 3b = 3 × 5 = 15 cm }}$

Hence, the length and width of the rectangle are 15 cm and 5 cm% respectively.