Question

How do you show perpendicular lines?

Answer 1

To show perpendicular lines:

Suppose we have two lines $I$ and $n$, whose slopes are $m_1$and $m_2$.

If $I$ and $n$ are perpendicular , then, ${\mathit{m}}_{\mathbf{1}}\mathbf{.}{\mathit{m}}_{\mathbf{2}}\mathbf{=}\mathbf{-}\mathbf{1}$

Hence ,this condition shows that the lines are perpendicular.