A radio wave with a wavelength of 1200 m follows two paths to a receiver that is 25.0 km away. One path goes directly to the receiver and the other reflects from an airplane that is flying above the point that is exactly halfway between the transmitter and the receiver. Assume there is no phase change when the wave reflects off the airplane. If the receiver experiences destructive interference, what is the minimum possible distance that the reflected wave has traveled? For this distance, how high is the airplane?