#### Answer

$(\frac{s}{2},\frac{s}{2})$ and $(\frac{s}{2},\frac{s}{2})$

#### Work Step by Step

Step 1. Use the given Hint, we have on diagonal as from $(0,0)$ to $(s,s)$, and we can find its midpoint as $(\frac{s}{2},\frac{s}{2})$.
Step 2. The other diagonal is from $(0,s)$ to $(s,0)$, and we can find its midpoint as $(\frac{s}{2},\frac{s}{2})$ which is the same as in Step 1.
Step 3. Thus, we can draw the conclusion that the diagonals of a square intersect at their midpoints.