http://www.ck12.org Chapter 3. Parallel and Perpendicular Lines
down 1 from 2 and over to the right 2 from -1, you will hity= 2 x−1 at (1, 1). Use these two points to determine
the distance between the two lines.
d=√
( 1 + 1 )^2 +( 1 − 2 )^2
=
√
22 +(− 1 )^2
=
√
4 + 1
=
√
5 ≈ 2. 24 unitsThe lines are about 2.24 units apart.
Notice that you could have used any two points, as long as they are on the same perpendicular line. For example,
you could have also used (-3, -2) and (-1, -3) and you still would have gotten the same answer.
d=√
(− 1 + 3 )^2 +(− 3 + 2 )^2
=
√
22 +(− 1 )^2
=
√
4 + 1
=
√
5 ≈ 2. 24 unitsExample C
Find the distance between the two parallel lines below.