求解一道AP微积分题!At noon,ship A is 40 nautical miles due east of s
求解一道AP微积分题! At noon,ship A is 40 nautical miles due east of ship B.Ship A is sailing east at 25 knots and ship B is sailing north at 20 knots.How fast (in knots) is the distance between the ships changing at 4 PM?(Note:1 knot is a speed of 1 nautical mile per hour.)