Chapter 2.6, Problem 19AYU

19. Uniform Motion Two cars are approaching an intersection. One is 2 miles south of the intersection and is moving at a constant speed of 30 miles per hour. At the same time, the other car is 3 miles east of the intersection and is moving at a constant speed of 40 miles per hour.

Build a model that expresses the distance d between the cars as a function of time t.

[Hint: At $t\text{ = 0}$, the cars are 2 miles south and 3 miles east of the intersection, respectively.]

(b) Use a graphing utility to graph $d\text{ = }d\left(t\right)$. For what value of t is d smallest?