Question

how is the slope formula used to identify parallel and perpendicular lines

Answer 1

there really isnt a formula. Parallel line have the same slope, while perpendicular lines have the negative reciprocal of the slope

Answer 2

lets consider two lines
\[y=m_1x+c_1............(1)\]and
\[y=m_2x+c_2.................(2)\]
where
m_1=slope of the first line and
m_2=slope of the second line
then
those lines will be parallel only when
\[\boxed {m_1=m_2}\]
and they will be perpendicular when\[\boxed{m_1*m_2=-1}\]

Answer 3

Both answers help thank you :)