Question:
Mark $(\sqrt{)}$ against the correct answer in each of the following:
If $A(1,2,-3)$ and $B(-1,-2,1)$ are the end points of a vector $\overrightarrow{A B}$ then the direction cosines of $\overrightarrow{\mathrm{AB}}$ are
A. $-2,-4,4$
B. $\frac{-1}{2},-1,1$
C. $\frac{-1}{3}, \frac{-2}{3}, \frac{2}{3}$
D. none of these
Solution:
