# At noon, ship A is 30 nautical miles due west of ship B. Ship A is sailing west at 16 knots and ship B is sailing north at 21 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 h

##### 1 Answer

#### Answer:

#### Explanation:

Consider a cartesian coordinate system in which X axis is oriented East and Y axis is oriented North.

"**at 4 pm**" is just a red herring.