ExamBro
ExamBro
MHT CET · Maths · Three Dimensional Geometry

If the line \(\frac{x-1}{2}=\frac{y+1}{3}=\frac{z-2}{4}\) meets the plane \(x+2 y+3 z=15\) at the point \(\mathrm{P}\), then the distance of \(\mathrm{P}\) from the origin is

  1. A \(\frac{7}{2}\) units
  2. B \(\frac{9}{2}\) units
  3. C \(\frac{\sqrt{5}}{2}\) units
  4. D \(2 \sqrt{5}\) units
Verified Solution

Answer & Solution

Correct Answer

(B) \(\frac{9}{2}\) units

Step-by-step Solution

Detailed explanation

Let \(\frac{x-1}{2}=\frac{y+1}{3}=\frac{z-2}{4}=\mathrm{k}\) (say)
Let \(\mathrm{P}\) be the any point on the above line.
\(\therefore \quad \mathrm{P}=(2 \mathrm{k}+1,3 \mathrm{k}-1,4 \mathrm{k}+2)\)
The point \(\mathrm{P}\) lies on the plane
\(\begin{array}{ll}
\therefore & 2 \mathrm{k}+1+2(3 \mathrm{k}-1)+3(4 \mathrm{k}+2)=15 \\
\therefore & 2 \mathrm{k}+1+6 \mathrm{k}-2+12 \mathrm{k}+6=15 \\
\therefore & 20 \mathrm{k}=10 \\
\therefore & \mathrm{k}=\frac{1}{2} \\
\therefore & \mathrm{P}=\left(2, \frac{1}{2}, 4\right)
\end{array}\)
Distance of \(\mathrm{P}\) from origin is
\(\sqrt{2^2+\left(\frac{1}{2}\right)^2+4^2}=\sqrt{\frac{81}{4}}=\frac{9}{2}\)