Posted by Tina on .
An airplane is flying east at a constant altitude of 28,000 meters. When first seen to the east of an observer, the angle of elevation to the airplane is 71.5 degrees. After 73 seconds, the angle of elevation is 51.6 degrees. Find the speed of the airplane.

Math (PreCalc) 
Henry,
tan71.5 = Y/X = 28,000 / X.
X = 28,000 / tan71.5 = 9369 m. = d1.
X = 28,000 / tan51.6 = 22,193 m.= d2.
V = d/t = (d2d1)/t.
V = (22,1939369) / 73 = 176 m/s.