Is there a relationship between the area and the perimeter of a rectangle?

The are is A=W*L
The perimeter is P=2L+2W
So there is some form of relationship.
A/W=L and P-2W=2L
A/W=L and (P-2W)/2=L
A/W=(P-2W)/2
2A/W=P-2W
2A=PW-2W^2
If you line them up according to the quadratic formula you can have 
2W^2-PW+2A=0 where W is the variable equivalent to X in normal circumstances and P and A are set values.  There is always a relationship between two numbers, or at least you can almost always create your own relationship.  This may seem rather complicated but this is a complicated question and I applaud you for asking something of this sort.

A= r2 × 3.14 11×11 ↓ ↓ 121 × 3.14 = 379.94 → 379.9