Angle between Lines (Leaving Cert Mathematics): Flashcards

Angle between two intersecting lines

$\tan \theta = \left| \frac{m_2 - m_1}{1 + m_1m_2} \right|$

$m_1m_2 = -1$

$90^\circ$

$m_1 = m_2$

$0^\circ$

$1 + m_1m_2 \neq 0$

$\tan \theta = |m_2|$

Identify the slopes of the lines

Use inverse tangent

$\infty$ (infinity)