2. $O P E N$ is a square, and $T$ is a point on side $N O$, such that triangle $T O P$ has area 62 and triangle $T E N$ has area 10 . What is the length of a side of the square?
Solution:
12
$62=P O \cdot O T / 2$ and $10=E N \cdot T N / 2=P O \cdot T N / 2$, so adding gives $72=P O \cdot(O T+$ $T N) / 2=P O \cdot O N / 2=P O^{2} / 2 \Rightarrow P O=12$.