The angle θ between two lines having slopes m1 and m2 is given by

• A. \(\tan \theta = \frac{{\left( {{m_1} - {m_2}} \right)}}{{{m_1}{m_2}}}\)
• B. \(\tan {\rm{\theta }} = \frac{{{{\rm{m}}_1} - {{\rm{m}}_2}}}{{1 + {{\rm{m}}_1}{{\rm{m}}_2}}}\)
• C. \(\tan \theta = \frac{{\left( {{m_1} + {m_2}} \right)}}{{{m_1}{m_2}}}\)
• D. \(\tan \theta = \frac{{\left( {{m_1} - {m_2}} \right)}}{{{m_1} + {m_2}}}\)