For a your meant to draw a graph (I don’t know what graph) and for b use the domain to figure out the minimum and maximum range values
The general formula for the distance between two points is

Anyway, if A and B have the same x or y coordinates, this formula can be simplified. For example, in this case the two points have the same x coordinate of -8, so the following part of the formula simplifies:

So, we're left with

but the square root of a square is the absolute value of the object being squared:

which is this case means 
which is the correct length of the side.
If the 316 is supposed to be 3/16 and the 34 is supposed to be 3/4, then your answer is 2.