A plane flying with a constant speed of 4 km/min passes over a ground radar station at an altitude of 13 km and climbs at an angle of 40 degrees. At what rate is the distance from the plane to the radar station increasing 4 minutes later?

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Answer 1 · 2016-05-04T04:15:26

#4.267# km.min

In t', the plane traverses 4t km.

So, the distance of the plane from the radar station t' later is

s(t) = #sqrt((4t)^2+13^2)# km.

#s'(t)=(16t)/sqrt(16t^2+169#) km/min

When t = 4, s'(4) = 64/15 = 4.267 km/min, nearly.