Question

The direction ratios of the line which is perpendicular to the lines $\frac{ x - 7}{2} = \frac{y +17}{-3}= \frac{z - 6}{1}$ and $\frac{ x + 5}{1} = \frac{y +3}{2}= \frac{z - 4}{-2}$ are

• A. < 4, 5, 7>
• B. < 4, -5, 7 >
• C. < 4,-5,-7 >
• D. < -4, 5, 7 >

Answer 1

Answer: (A)

< 4, 5, 7>

Answer 2

Let d.rs of line are $< a, b, c >$, then
$2a-3b + C = 0$
and $a + 2b - 2c = 0$
$\Rightarrow \:\: \frac{a}{6 -2} = \frac{b}{1 + 4}= \frac{c}{4 + 2} \:\: \Rightarrow \: \frac{a}{4} = \frac{b}{5} = \frac{c}{7}$
$\therefore$ d.rs of line are $< 4, 5, 7 >$