A man standing in a point C of a ground. He observes a flying an aero-plane in the east at an angle of elevation of 30° and after 30 seconds, he observes the same aero-plane in the west at an angle of elevation of 60°. If the aero-plane flies all along in a straight line at a height of 480√3 m, then its speed in km/h is:

A man standing in a point C of a ground. He observes a flying an aero-

1.	A man standing in a point C of a ground. He observes a flying an aero-plane in the east at an angle of elevation of 30° and after 30 seconds, he observes the same aero-plane in the west at an angle of elevation of 60°. If the aero-plane flies all along in a straight line at a height of 480√3 m, then its speed in km/h is:
A.	249.8
B.	230.4
C.	247.8
D.	257.5
Answer» C. 247.8