The angle between two lines y = m1x + c1 and y = m2x + c2 is
1
\(\rm \tan^{-1} \left(\frac{m_1 - m_2}{1-m_1m_2} \right )\)
2
\(\rm \pm \tan^{-1} \left(\frac{m_1 - m_2}{1+m_1m_2} \right )\)
3
\(\rm \pm \tan^{-1} \left(\frac{m_1 + m_2}{1+m_1m_2} \right )\)
4
None of the above
5
Question Not Attempted