Question: An ariplane is flying east at a constant altitude of 30,500 meters. When first seen to the east of an observer, the angle of elevation to the airplane is 63.6 degrees. After 33 seconds, the angle of elevation is 56.1 degrees. Find the speed of the airplane.
A) 163 m/s
B) 158 m/s
C) 379 m/s
D) 392 m/s