The perimeter of the circular plot is twice the perimeter of a rectangular field whose length and breadth is x m and (x – 12) m, respectively. If the area of the rectangle field is 1260 meter sq., then, find the cost(in Rs) of fencing of the circular plot at the rate of Rs. 5 per m.

Correct option is D

x(x-12)=1260
x² - 12x – 1260 = 0
x = 42, -30
x = 42
Perimeter of rectangular field = 2(42+30)= 144 m
Perimeter of circular plot = 2 (144) = 288 m
Required cost = 288×5 = Rs 1440