General: Rockets A rocket fired straight up is being tracked by a radar station 3 mile...

General: Rockets A rocket fired straight up is being tracked by a radar station 3 miles from the launching pad. If the rocket is traveling at 2 miles per second, how fast is the distance between the rocket and the tracking station changing at the moment when the rocket is 4 miles up? [Hint: The distance D in the illustration satisfies D² = 9+y². To find the value of D, solve D² = 9+4².]