Finding the Dead Frequencies. A football field is a rectangle of width 53.3 yards (48.8 m) and length 100 yards (91.4 m). The goal lines are on the extremes (100 yards apart) with the 50-yard line at the center. Yard lines are drawn every 5 yards and labeled every 10 yards, counting up from each goal line to the 50-yard line. To the left and right of the midfield line (that is, the 50-yard line) are the 40- yard lines, then the 30-yard lines, and so on. A new announcer box was constructed near the football field, centered on the 50-yard line, and 20.0 yards away from the sideline. Two loudspeakers are mounted on the upper left and right corners of the box, which is 12.0 yards wide. You and your team have been assigned to identify all frequencies between 0 Hz and 1.25 kHz for which dead spots occur due to destructive interference at the 35.0-yard markers on the opposite side-line. Assume that the speakers are in phase, and that the speed of sound in air is 343 m/s. You can neglect the height of the speakers above the ground. Type your answers from lowest to highest. Number i Number i Number Number Number Number i Number i i i Number i i Units Units Units Units Units Units Units Units