Answer
$\text{i. The lines are parallel if } m_1=m_2$
$\text{ii. The lines are perpendicular if } m_1=-\frac{1}{m_2}.$
Work Step by Step
The lines are parallel if they have equivalent slopes. Since $m_1=m_2$ indicates equivalent slopes, if this is the case then the lines are indeed parallel.
The lines are perpendicular if the slopes are negative reciprocals. $-\frac{1}{m_2}.$ is the negative reciprocal of $m_2$.
