Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Three-dimensional Geometry

Question:

Let A(2, -1, 4) and B(0, 2, -3)  be two points and C be a point on AB produced such that 2 AC = 3 AB, then the coordinates of C are

Options:

$\left(\frac{1}{2}, \frac{5}{4}, -\frac{5}{4}\right)$

$\left(-\frac{1}{2}, \frac{7}{4}, -\frac{13}{4}\right)$

$(6, -7, 18)$

none of these

Correct Answer:

none of these

Explanation:

We have, 

2 AC = 3 AB

$⇒ 2AC = 3 (AC - BC) ⇒ AC = 3 BC ⇒ \frac{AC}{BC}= \frac{3}{1}$

⇒  C divides AB externally in the ratio 3 : 1.

∴ Coordinates of C are

$\left(\frac{3×0-2×1}{3-1},\frac{3×2-1×-1}{3-1}, \frac{3×(-3)-1×4}{3-1}\right) or, \left(-1, \frac{7}{2}, \frac{-13}{2}\right)$