Answer:
21 ft by 28 ft
Step-by-step explanation:
To maximize the area, see the attached.
Perimeter will be 4l+3w which is equal to the fencing perimeter, given as 168
4l+3w=168
Making l the subject then
4l=168-3w
l=42-¾w
Area of individual land will be lw and substituting l with l=42-¾w
Then
A=lw=(42-¾w)w=42w-¾w²
A=42w-¾w²
Getting the first derivative of the above with respect to w rhen
42-w6/4=0
w6/4=42
w=42*4/6=28
Since
l=42-¾w=42-¾(28)=21
Therefore, maximum dimensions are 21 for l and 28 for w
