HINT

let length of rectangular field be a and width be b

area =ab=c=1.5 million square feet(that is a constant)

for minimizing the cost of fence perimeter(p) should be minimum.

Let p=2(a+b)

p=2(a+c/a)

find dp/da and equate it to 0 to get the value of a

then get value of b from ab=c

Then divide the area by fencing parallel to the smaller side.