At noon, ship A is 20 nautical miles due west of ship B. Ship A is sailing west at 23 knots and ship B is sailing north at 17 knots. How fast (in knots) is the distance between the ships changing at 5 PM? (Note: 1 knot is a speed of 1 nautical mile per hour.)

Answer 1

draw the diagram.

I see this

d= sqrt(ND^2+(WD+20)^2) where ND is north distance, WD is west distance
take the derivative

d'= 1/2 *1/(sqrt( ) * 2ND*ND'+2(WD+20)(WD')

ND= 17kt/hr*5hrs ND'=17kts/hr
WD=23*5 WD'=23

have fun.

Answer 2

what do you mean by 1/(sqrt()?

Answer 3

what do you mean by 1/(sqrt()?