A kite is moving horizontally at a height of 151.5 meters. If the speed of kite is 10m/s,

A kite is moving horizontally at a height of 151.5 meters. If the speed of kite is 10m/s how fast is 250 m away from the boy who is flying the kite ? The height of boy is 1.5 m.

We have, height (h) = 1515. m, speed of kite(v) = 10 m/s,Let CD be the height of kite and AB be the height of body. ,∴ dx/dy = 10 ,From the figure, we have ,EC = 151.5 - 1.5 = 150 m,and AE = x,Also, AC = 250 m,In right angled △CEA,,AE,2, + EC,2, = AC,2, ,⇒ x,2, + (150)2 = y,2, ,Differentiating w.r.t.x, we get