P$16\mathrm{.}43.$ An eight$-$pole $240-$V$-$rms $60-$Hz delta$-$connected synchronous motor operates with a constant developed power of $50$ hp $,$ unity power factor, and a torque angle of $\backslash (15^\{\backslash$circ$\}\backslash ).$ Then, the field current is increased such that Br increases in magnitude by $20$ percent. Find the new torque angle and power factor. Is the new power factor leading or lagging?