i have 50 feet of fence and the house will be the fourth side. i want a rectangular fence as big as possible. what re the dimensions?

I assume largest area.

P=w+2l
area= wl
area= (50-2l)l
area= 50l-2l^2

darea/dl= 0= 50-4l
l=12.5, and w=25. In reality, one cannot adjust the size of a house to fit the area enclosed.