Given:
\[\cot \theta + \sec \theta = m \implies \sec \theta = m - \cot \theta\]
Using identities:
\[\cot^2 \theta + 1 = \csc^2 \theta, \quad \csc^2 \theta - \sec^2 \theta = 1.\]
After simplification:
\[\sec \theta = \frac{m^2 + 1}{2m}.\]
Correct Answer: Proved
The direction cosines of two lines are connected by the relations \( 1 + m - n = 0 \) and \( lm - 2mn + nl = 0 \). If \( \theta \) is the acute angle between those lines, then \( \cos \theta = \) ?