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AP EAMCET · Maths · Three Dimensional Geometry

If the direction ratios of two lines are given by 3lm − 4ln + mn = 0 and l + 2m + 3n = 0, then the angle between the lines is

  1. A \(\frac{\pi}2\)
  2. B \(\frac{\pi}{3}\)
  3. C \(\frac{\pi}{4}\)
  4. D \(\frac{\pi}{6}\)
Verified Solution

Answer & Solution

Correct Answer

(A) \(\frac{\pi}2\)

Step-by-step Solution

Detailed explanation

Given, 3lm − 4ln + mn = 0 … (i) l + 2m + 3n = 0 … (ii) \(\Rightarrow \quad l=-2 m-3 n\) From Eq. (i), we get 3(− 2m − 3n)m − 4(− 2m − 3n) n + mn = 0 \(-6 m^2-9 n m+8 m n+12 n^2+m n=0\)…