Question

The length of a rectangular park is 4 m more than thrice its breadth. What is the length and breadth of the pool if its perimeter is 420 m​

Answer 1

Given:- the length of a rectangular park is 4m more than thrice of its breadth and its perimeter is 420m.

To find:- length and breadth of park.

Solution :-

Let the breadth of rectangular park is xm.

∴ length = 4 + 3(breadth)

length = 4 + 3x....eq.1

From second given condition, perimeter is 420.

Perimeter of rectangle = 2( length + breadth )

⇒420 = 2(4 + 3x + x) ...from eq.1

⇒ 420 = 2(4+4x)

⇒ 420 = 8 + 8x

⇒ 8x = 412

⇒ x = 412/8

⇒ x = 51.5m

• Breadth = x = 51.5m

• Length = 4+3x = 4+3(51.5) = 158.5m

More important formulas:

Area of rectangle = length + breadth

Perimeter of square = 4×side

Area of square = side × side

Area of right angled triangle = 1/2 × base × height

Area of parallelogram = base × height

Answer 2

Given that ,

• The length of a rectangular park is 4 m more than thrice its breadth

• The Perimeter of rectangular park is 420 m

Let ,

• Breadth of rectangle be " x "
• Then , length = " 3x + 4 "

We know that , the perimeter of rectangle is given by

$\boxed{ \tt{Perimeter = 2(l + b) }}$

Thus ,

420 = 2(3x + 4 + x)

210 = 4x + 4

206 = 4x

x = 206/4

x = 51.1 m

∴

• Breadth = 51.1 m
• Length = 3(51.1) + 4 = 157.3 m