The drill bit of a variable$-$speed electric drill has a constant angular acceleration of $2\mathrm{.}74$ rad$/$s$?.$ The initial angular speed of the bit is $6\mathrm{.}36$ rad$/$s$.$ After $4\mathrm{.}26$ s$,($a$)$ what angle has the bit turned through and $($b$)$ what is the bit's angular speed?

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