B is the answer because it does not give information for the third side. We cannot assume it is equal because it is not a right triangle.
First simplify this inequality:

Now you can graph this inequality. Draw the vertical dashed line x=3 and shade the region to the right from this line. This is exactly the region that represents the solution of inequality (see attached diagram for details).
No, the longest chord possible is equal to the diameter...
C=2πr=2·π·13≈81.68141
C=81.68