a police cruiser approaching a right-angled intersection from the south, is chasing a speeding car that has turned the corner and now is moving straight west. When the cruiser is 0.9 mile south of the intersection and the car is 1.2 miles to the west, the police officers determine with radar that the distance between them and the car is increasing at 25 mph. If the cruiser is moving at 60 mph at the instant of measurement, what is the speed of the car?

Need to use derivatives