Let $3 \mathbf{i}-\mathbf{j}+4 \mathbf{k}, \vec{j}-2 \mathbf{k}, \mathbf{i}-3 \mathbf{j}+\mathbf{k}$ be three vectors with tails at the origin. Then their heads determine three points $A, B, C$ in space which form a triangle. Find vectors representing the sides $A B, B C, C A$ in that order and direction (for example, $A$ to $B$, not $B$ to $A$ ) and show that the sum of these vectors is zero.