Select the single best definition that describes two perpendicular lines.
Two lines that intersect each other at an angle of 90°.
Two lines that have only one intersection.
Two lines whose product of gradients is equal to $1$1.
Two lines that have no intersections.
If two lines are perpendicular, what is the product of their gradients?
Are the lines $y=x+2$y=x+2 and $y=x-2$y=x−2 perpendicular?
Are the following lines perpendicular:
$L_1$L1: $y=7x-5$y=7x−5
$L_2$L2: $y=-7x+6$y=−7x+6