The direction cosines of the line passing through the point P(1,2,−5) and Q(–1,−2,3) is (a) (1√21,2√21,4√21)(b) (−1√21,−2√21,−4√21) (c) (−1√21,−2√21,4√21)(d) (1√21,2√21,−4√21)

The direction cosines of the line passing through the point P(1,2,−5

1.	The direction cosines of the line passing through the point P(1,2,−5) and Q(–1,−2,3) is (a) (1√21,2√21,4√21)(b) (−1√21,−2√21,−4√21) (c) (−1√21,−2√21,4√21)(d) (1√21,2√21,−4√21)
Answer» The direction cosines of the line passing through the point $P (1, 2, - 5)$ and $Q (- 1, - 2, 3)$ is $(a) (\frac{1}{\sqrt{21}}, \frac{2}{\sqrt{21}}, \frac{4}{\sqrt{21}}) (b) (- \frac{1}{\sqrt{21}}, - \frac{2}{\sqrt{21}}, - \frac{4}{\sqrt{21}})$ $(c) (- \frac{1}{\sqrt{21}}, - \frac{2}{\sqrt{21}}, \frac{4}{\sqrt{21}}) (d) (\frac{1}{\sqrt{21}}, \frac{2}{\sqrt{21}}, - \frac{4}{\sqrt{21}})$