Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Three-dimensional Geometry

Question:

The distance of the point (-1, 2, 6) from the line $\frac{x-2}{6}=\frac{y-3}{3}=\frac{z+4}{-4}$, is equal to :

Options:

7 units

9 units

10 units

12 units

Correct Answer:

7 units

Explanation:

Any point on the line is

P = (6r1 + 2, 3r1 + 3, –4r1 – 4)

Direction ration of the line segment PQ, where Q = (–1, 2, 6), are

6r1 + 3, 3r1 + 1, – 4r, – 10

If ‘P’ be the foot of altitude drawn from Q to the given line, then

6(6r1 + 3) + 3(3r1 + 1) + 4(4r1 + 10) = 0

⇒ r1 = –1

Thus, P = (–4, 0, 0)

∴ Required distance = $\sqrt{9+4+36}$

= 7 units