calculus
posted by fareha .
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?

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