A gas station stands at the intersection of a north-south road and an east-west road. A police car is traveling toward the gas station from the west, chasing a stolen truck which is traveling north away from the gas station. The speed of the police car is 90 mph at the moment it is 5 miles from the gas station. At the same time, the truck is 12 miles from the gas station going 70 mph. a. At this time, The distance between the car and truck is decreasing at a rate of mph :
b. Is the distance between the police car and the truck increasing or decreasing?
c. When the truck is 4 miles from the gas station and the police car is 3 miles from the gas station, how fast is the distance between the police car and the truck changing?
d. At the same instant, how fast is the angle changing which has the police car as its vertex?