CK-12 Geometry-Concepts

3.8. Parallel Lines in the Coordinate Plane http://www.ck12.org

Example C

Find the equation of the line that is parallel to the line through the point marked with a blue dot.

First, notice that the equation of the line isy= 2 x+6 and the point is (2, -2). The parallel would have the same slope
and pass through (2, -2).

y= 2 x+b

− 2 = 2 ( 2 )+b

− 2 = 4 +b

− 6 =b

The equation of the parallel line isy= 2 x+−6.

Watch this video for help with the Examples above.

MEDIA

Click image to the left for use the URL below.

URL: http://www.ck12.org/flx/render/embeddedobject/52439

CK-12 Foundation: Chapter3ParallelLinesintheCoordinatePlaneB

Vocabulary

Two lines in the coordinate plane with the same slope areparalleland never intersect.Slopemeasures the steepness
of a line.

Guided Practice

1. Which of the following pairs of lines are parallel?
   
   
   • y=− 3 x+1 andy= 3 x− 1