Question

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

• A. $ \frac{\pi}{4} $
• B. $ \frac{\pi}{3} $
• C. $ \frac{\pi}{2} $
• D. $ 0 $

Hint:

In problems involving homogeneous equations in $ l, m, n $, always aim to reduce the system to a quadratic in terms of a ratio like $ l/m $ or $ m/n $.

Answer 1

The Correct Option is C