Static interference on radios may be due to the destructive interference of radio waves at the same frequency arriving at the receiver after traveling different distances. Suppose a radio wave with a wavelength of 1000 m travels two different paths from a radio tower located 20 km away. The first path is the most direct path. The second path is a result from the wave reflecting off of an airplane at an unknown altitude above a point that is exactly halfway between the tower and receiver. Assume there is no phase change when the wave reflects off the airplane. a. What is the speed and frequency of the radio waves? b. What is the minimum possible distance that the reflected wave has traveled? c. What is the time difference between arrivals at the receiver for the two destructively interfering waves? d. What is the altitude of the airplane (ignore curvature of Earth)? e. Reconsider the initial assumption. Let there be a 180 degree phase change in the wave reflecting off of the airplane. Does the airplane have a higher or lower altitude than what was calculated in part d? Why?