Question

two lines are perpendicular when
the product of their slope is -1
the product of their slope is greater than 0
they have the same slope
their slopes are undefined

Answer 1

is it the first one

Answer 2

lines are perpendicular when their slopes are negative reciprocals of each other

Answer 3

so it is the first one?

Answer 4

ex: \[\frac{ 3 }{ 4 }*\frac{ -4 }{ 3}=-1\]
yes it is the first one