Answer:
B. 3.45
Step-by-step explanation:
The radius is half the diameter
By the law of cosines, the angle

satisfies

which reduces to

which converts to approximately 77 degrees (this can be done my multiplying by 180 and dividing by pi).
Since the block is a cube, the dimentions from corner to corner equal all the same, as long as the pieces are equal, which in this case, they are. :) So basically what you need to do is find the perimeter of one side of the cube, and that's the answer.
(x-9)(x-3), because -9 and -3 make a sum of -12 and a product of +27