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AP EAMCET · Maths · Three Dimensional Geometry

Let \(P\left(x_1, y_1, z_1\right)\) be the foot of perpendicular drawn from the point \(Q(2,-2,1)\) to the plane \(x-2 y+z=1\). If \(d\) is the perpendicular from the point \(Q\) to the plane and \(l=x_1+y_1+z_1\), then \(l+3 d^2\) is

  1. A 5
  2. B 7
  3. C 19
  4. D 26
Verified Solution

Answer & Solution

Correct Answer

(C) 19

Step-by-step Solution

Detailed explanation

\(\begin{aligned} & \text { } \frac{x_1-2}{1}=\frac{y_1+2}{-2}=\frac{z_1-1}{1}=\frac{-(2+4+1-1)}{6} \\ & x_1=1, y_1=0, z_1=0 \Rightarrow l=1+0+0=1 \\ & d=\left|\frac{2+4+1-1}{\sqrt{6}}\right|=\sqrt{6} \\ & \Rightarrow l+3 d^2=19\end{aligned}\)