$42.$ Consider an array of parallel wires with uniform spacing of $1\mathrm{.}30$ cm between centers. In air at $20\mathrm{.}0$C$,$ ultrasound with a frequency of $37\mathrm{.}2$ kHz from a distant source is incident perpendicular to the array. $($Take the speed of sound to be $343$ m$/$s$.)($a$)$ Find the number of directions on the other side of the array in which there is a maximum of intensity. $($b$)$ Find the angle for each of these directions relative to the direction of the incident beam.