m = ( 3 – 7 )/( 1 -(-4)) = -4/5

For line 2 m = (10 -6)/( 4-2) = 4/2 = 2

If the slopes of the lines are the equal, the lines are parallel. If the product of the slopes is -1 the lines are perpendicular. Since the lines do not have equal slopes lines 1 and 2 are NOT parallel. The product of their slopes.

(-4/5)(2/1) = -8/5 is clearly not -1, so these two lines are not perpendicular either.

What you need to do to finish the problem is find the slopes of lines 3 & 4 to find any equal slopes as your test for parallel lines. Multiply each negative slope with each positive slope to find those whose product is -1. This is your test for perpendicular lines.

Good luck!

When gradient is the same this means parallel

when grad1xgrad2 = -1 means perpendicular

line1 and line 2:

1: 3-7/1-(-4) = -4/5

2: 10-6/4-2 = 4/2

not parallel

-4/5 x 4/2 = -8/5

so not perp