Question

The direction cosines of the line drawn from P(–5, 3, 1) to Q(1, 5, –2) is

• A. $(6,2,-3)$
• B. $(2,-4,1)$
• C. $(-4,8,-1)$
• D. $(\frac{6}{7},\frac{2}{7},-\frac{3}{7})$

Answer 1

The correct option is D $(\frac{6}{7},\frac{2}{7},-\frac{3}{7})$

DR’s of PQ are 1 – (–5), 5 – 3, – 2 – 1
ie., 6, 2, –3
$and\sqrt{6^2+2^2+(-3{)}^2}=7\therefore D{C}^{\prime }sare\frac{6}{7},\frac{2}{7},-\frac{3}{7}$