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 $\sqrt{6^2+2^2+(-3{)}^2}=7$
$\therefore$ DC's are $\frac{6}{7},\frac{2}{7},\frac{3}{-7}$