Answer
a). Yes.
b). We construct vectors A+B, and B+C.
Then we add C to A+B, and
add A to B+C.
As we can see the sum of the 3 vectors end at the same point.
So, vectors (B+C)+A=A+(B+C).
Work Step by Step
a). Yes.
b). We construct vectors A+B, and B+C.
Then we add C to A+B, and
add A to B+C.
As we can see the sum of the 3 vectors end at the same point.
So, vectors (B+C)+A=A+(B+C).