Question

in a plane, if two lines are perpendicular to the same line, then they are what to each other.

Answer 1

Have you tried drawing a sketch?

1) Draw a line.
2) Make a second line perpendicular (90 degrees) to the first one.
3) Draw another line perpendicular to the very first line.

How are lines 2 and 3 related? (parallel, perpendicular, intersecting at 45 degrees, etc?)

Hope this helps.

Answer 2

You can also think about slope. if they are mutually perpendicular to a common line of arbitrary slope, how are their slopes related?

(perpendicular lines have opposite reciprocal slopes)

Answer 3

they are parallel aren't they

Answer 4

that's right

Answer 5

if the common line has slope a, the two perpendiculars have slope -1/a. Since their slope is the same they are parallel

Answer 6

what are the exterior angles of a triangle is it 360 degrees