A plane flying horizontally at an altitude of 2 mi

Question

A plane flying horizontally at an altitude of 2 mi and a speed of 580 mi/h passes directly over a radar station. Find the rate at which the distance from the plane to the station is increasing when it is 4 mi away from the station. (Round your answer to the nearest whole number.) 

Answer 1

Draw a figure which shows a right triangle with a vertical leg of 2 and horizontal leg of x and hypotenuse y.

y² = x² + 4

When y = 4, x = 2√3 and y(dy/dt) = x(dx/dt)

You now have all the information you need to answer the question. Note that dx/dt = 580

Answer 2