Question

A plane flying horizontally at an altitude of 1 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 2 mi away from the station. Round your answer to the nearest whole number.

Answer 1

 the tangent function of 2mi/5mi = 21.8 degrees
cosine of that angle = cos (21.8 degrees)
                                =0.928
 multiply 0.928 with 570 = 570*0.928
     Closing velocity         =  529.23 mph
As the plane gets closer to radar station, tangent function becomes infinity and the cosine function becomes zero.....
0*570 = 0