At 2:00 PM bike A is 4km north of point C and traveling south at 16km/h. At the same time, bike B is 2km east of C and traveling east at 12km/h.

a. Show that t hours after 2:00 PM the distance between the bikes is:

square root of 400t^2 - 80t + 20

b. At what time is the distance between the bikes the least?

Help would really be appreciated!

Thanks!!!