Distance between the two planes: 2x+3y+4z = 4 and 4x+6y+8z = 12 is
2 units
\(\frac {2}{\sqrt 29}\) units
The equation of the planes are
2x+3y+4z = 4 ...(1)
4x+6y+8z = 12
⇒2x+3y+4z = 6 ...(2)
It can be seen that the given planes are parallel. It is known that the distance between two parallel planes, ax+by+cz=d1 and ax+by+cz=d2, is given by,
D = \(|\frac {d_2-d_1}{√a^2+b^2+c^2}|\)
⇒ D = \(|\frac {6-4}{√2^2+3^2+4^2}|\)
D = \(\frac {2}{\sqrt 29}\)
Thus, the distance between the lines is \(\frac {2}{\sqrt 29}\) units.
Hence, the correct answer is D.
Let the lines $L_1 : \vec r = \hat i + 2\hat j + 3\hat k + \lambda(2\hat i + 3\hat j + 4\hat k)$, $\lambda \in \mathbb{R}$ and $L_2 : \vec r = (4\hat i + \hat j) + \mu(5\hat i + + 2\hat j + \hat k)$, $\mu \in \mathbb{R}$ intersect at the point $R$. Let $P$ and $Q$ be the points lying on lines $L_1$ and $L_2$, respectively, such that $|PR|=\sqrt{29}$ and $|PQ|=\sqrt{\frac{47}{3}}$. If the point $P$ lies in the first octant, then $27(QR)^2$ is equal to}
