arcs are just sections of the circle
so lets say you had a pizza
and you put some points on the crust, the legnth of the crust from point to point is that arc
example
if you put poins A and B, then arc AB is the crust between points A and B
arcs can include other points as well
and arc AB=arc BA
so
I wil name easy arcs first
arc AB
arc BC
arc CD
ard DA
now ones that include others
arc AC
arc BD
so the arcs you might want to list are
arc AB
arc BC
arc CD
ard DA
arc AC
arc DB