A wire of length 6 is cut into two pieces which are then bent into the shape of a circle of radius $r$ and a square of side $s$. Then the total area enclosed by the circle and square is the following function of $s$ and $r$

If we solve for $s$ in terms of $r$, we can reexpress this area as the following function of $r$ alone:

Thus we find that to obtain maximal area we should let $r=$
To obtain minimal area we should let $r=$