Posted by fareha on .
if a farmer has 100 feet of fence and wants to make a rectangular pigpen, one side of which is along existing straight fence.What dimensions should be used in order to maximize the area of the pen?

calculus 
drwls,
25  25  50
Maximum Area = 1250 ft^2
How to get that answer:
Let x be the side length that is used twice. The side parallel to the existing fence then has length 100  2x.
The area A is then
A(x) = x*(100  2x) = 100 x  2x^2
dA/dx = 0 when
100 = 4x
x = 25