A wheel's angular acceleration is constant. Initially its angular velocity is zero. During the first $1\mathrm{.}0-$s time interval $,$ it rotates through an angle of $90\mathrm{.}0.($a$)$ Through what angle does it rotate during the next $1\mathrm{.}0-$s time interval? $($b$)$ Through what angle during the third $1\mathrm{.}0-$s time interval?