Amy and Reno are on a flat surface. Amy is 2 km due (directly) North of Reno. At midday, Amy
starts walking slowly due East at 1 km/hr, while
Reno starts walking slowly due North at 1 km
per hour.

a). Find an expression for the square of the
distance between them after t hours.
b). Prove that this distance has a minimum
value of 2 km.
c). Find at what time this occurs.