The figure gives the path of a squirrel moving about on level ground, from point A $($at time t $=0),$ to points B $($at t $=5$ min$),$ C $($at t $=10$ min$),$ and finally D $($at t $=15$ min$).$ Consider the average velocities of the squirrel from point A to each of the other three points. Of them, what are the $($a$)$ magnitude and $($b$)$ angle of the one with the least magnitude and $($c$)$ the magnitude and $($d$)$ angle of the one with the greatest magnitude? Give the angles in the range $(-180\backslash$deg $,180\backslash$deg $]$