Question

A rectangular public park has an area of 3,600 square feet. It is surrounded on three sides by a chain link fence. If the entire length of the fence measures 180 feet, how many feet long could the unfenced side of the rectangular park be?

Answer 1

Answer:

If length of the field is 30 ft, then width is 120 ft.

If the  length of the field is 60 ft, then width is 60 ft.

Step-by-step explanation:

Let us assume the length of the rectangular park = L ft

Let us assume the breadth of the rectangular park = B  ft

Now, AREA of the given park =  L x B

⇒ L x B  = 3,600 sq ft   ... (1)

Also, the perimeter of three sides  = 180 ft

⇒ 2 L +  B  = 180  ..... (2)

Now, from (1) and (2), we get:

L x B  = 3,600

2 L +  B  = 180   ⇒ B  = 180 - 2 L

Substitute this in(1) , we get:

L x B  = 3,600   ⇒ L x (180 - 2 L)  = 3600

$\implies 180 L - 2L^2 = 3600\\\implies L^2 -90L + 1800 = 0\\\implies (L-30)(L-60)= 0$

⇒ L = 30 or L  = 60

So, if L  = 30  ft , then B = 180 - 2L  =  180 - 60 = 120 ft

So, if L  = 60  ft , then B = 180 - 2L  =  180 - 120 = 60 ft

So, if length of the field is 30 ft, then width is 120 ft.

And if the  length of the field is 60 ft, then width is 60 ft.