For this problem, we will need to use the formula for arc length, which is
, where
is the radius of the circle and
is the central angle in radians.
We can clearly see that the radius of the circle is 8. However, no central angle is given to us. However, we can see that the measure of arc AB is 45°. This means that the central angle of arc AB is also 45°. (Remember that the measure of arc is the same as the measure of its central angle.) Converting 45° to radians, we get
.
We can now plug this information into the formula to find our answer:

The answer is 2π.