$(12\mathrm{.}3$&$12\mathrm{.}4)$

Question $3,12\mathrm{.}3\mathrm{.}13$

Part $1$ of $3$

Find the measures of the angles of the triangle whose vertices are $A=(-2,0),B=(2,1),$ and $C=(1,-3).$

$\frac{m}{{?}_A}BC=$

$($Round to the nearest thousandth as needed.$)$