Given the points $A(5,7,-3),B(-4,1,0),$ and $C(-1,5,-1),$ find $($a$)$ the angle between vec$(AB)$ and vec$(AC),$

$($b$)$ the angle between vec$(BA)$ and vec$(BC),$ and tet the angle between vec$(CA)$ and vec$(CB).$

$($a$)\frac{?}{{?}_{B}AC}=*$

$($b$)\frac{?}{{?}_{A}BC}=$

$($c$)\frac{?}{{?}_{A}CB}=$

$0$