[填空题]
Consider two antennas radi;)htri4+ anbe ating 6.0-MHz radio waves in a b ir5dq,h/r d6qc:q1phase with each other. They are located at po5qi r b6qh,:rdd/1qacints $S_1$ and $S_2$, separated by a distance $d\;=\;175m$, Fig. 24–61. What are the first three points on the y axis where there will be destructive interference? (Destructive interference in this case means that a radio receiver placed at that point would pick up no signal). m m m
