Q32 / 90 · JEE Main 2012 (26 May Online) · Mathematics

Consider the following planes $$ \begin{aligned} & P: x+y-2 z+7=0 \\ & Q: x+y+2 z+2=0 \\ & R: 3 x+3 y-6 z-11=0 \end{aligned} $$

  • A
    $P$ and $R$ are perpendicular
  • B
    $Q$ and $R$ are perpendicular
  • C
    $P$ and $Q$ are parallel
  • Correct answer
    D
    $P$ and $R$ are parallel

Solution

Given planes are $$ \begin{aligned} & P: x+y-2 z+7=0 \\ & Q: x+y+2 z+2=0 \end{aligned} $$ and $R: 3 x+3 y-6 z-11=0$ Consider Plane $P$ and $R$. Here $a_1=1, b_1=1, c_1=-2$ and $a_2=3, b_2=3, c_2=-6$ Since, $\frac{a_1}{a_2}=\frac{b_1}{b_2}=\frac{c_1}{c_2}=\frac{1}{3}$ therefore $P$ and $R$ are parallel.

Hence, the correct answer is option: 'D'.

Relevant Questions