Question 73811
Call the slopes {{{m[1]}}} and {{{m[2]}}}
They are parallel if {{{m[1] = m[2]}}}
They are perpendicular if {{{m[1] = -1/m[2]}}}
Now find the slopes, which is (change in y) / (change in x)
{{{m[1] = (-7 - 3) / (-4 - 1)}}}
{{{m[1] = -10 / -5}}}
{{{m[1] = 2}}}
{{{m[2] = (6 - 10) / (2 - 4)}}}
{{{m[2] = -4 / -2}}}
{{{m[2] = 2}}}
{{{m[1] = m[2]}}}, so the lines are parallel