The direction cosines of the line joining the points (1, 1, -1) and (2, 3, 1) are:
1
\(\frac{1}{3},\frac{2}{3},\frac{1}{3}\)
2
\(\frac{1}{3},\frac{1}{3},\frac{1}{3}\)
3
\(\frac{1}{3},\frac{2}{3},\frac{2}{3}\)
4
\(\frac{1}{3},\frac{1}{3},\frac{2}{3}\)