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MHT CET · Maths · Three Dimensional Geometry

If the angle between the planes \(x-2 y+3 z-5=0\) and \(x+\alpha y+2 z+7=0\) is \(\cos ^{-1}\left(\frac{1}{14}\right)\) then the difference between the values of \(\alpha\) is

  1. A \(\frac{12}{11}\)
  2. B \(\frac{62}{55}\)
  3. C \(\frac{31}{11}\)
  4. D \(\frac{8}{5}\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(\frac{62}{55}\)

Step-by-step Solution

Detailed explanation

\(\vec{n_1} = \langle 1, -2, 3 \rangle, \vec{n_2} = \langle 1, \alpha, 2 \rangle\) \(\cos \theta = \frac{|\vec{n_1} \cdot \vec{n_2}|}{||\vec{n_1}|| \cdot ||\vec{n_2}||}\)