#### Problem 13E

(a) What quantities are given in the problem?

(b) What is the unknown?

(c) Draw a picture of the situation for any time $t$.

(d) Write an equation that relates the quantities.

(e) Finish solving the problem.

13. A plane flying horizontally at an altitude of $1 \mathrm{mi}$ and a speed of $500 \mathrm{mi} / \mathrm{h}$ passes directly over a radar station. Find the rate at which the distance from the plane to the station is increasing when it is $2 \mathrm{mi}$ away from the station.