A rectangular parking lot has a diagonal of $5$ meters and an area of $12$ square meters. In meters, what is the perimeter of the parking lot?

1. Let the side lengths be $a$ and $b$ meters. The diagonal and area give $a^2+b^2=5^2=25$ and $ab=12$.
2. Then $(a+b)^2=a^2+b^2+2ab=25+24=49$, so $a+b=7$ because both side lengths are positive.
3. The perimeter is $2(a+b)=14$ meters.