The projections of the line segment AB on the coordinate axes are –9, 12, -8 respectively. The direction cosines of the line segment AB are :

$-\frac{9}{17}, \frac{12}{17},-\frac{8}{17}$ $-\frac{9}{289}, \frac{12}{289},-\frac{8}{289}$ $-\frac{9}{\sqrt{17}}, \frac{12}{\sqrt{17}},-\frac{8}{\sqrt{17}}$ None of these

$-\frac{9}{17}, \frac{12}{17},-\frac{8}{17}$

Length of segment $AB=\sqrt{81+144+64}=17$ Thus direction cosines of AB are $-\frac{9}{17}, \frac{12}{17}, \frac{-8}{17}$