1. 3.6 Parallel Lines in the Coordinate Plane
Geometry
3.6 Parallel Lines in
the Coordinate Plane

2. SLOPE

3. Slope
Slope is usually represented by the variable m Always start with the point farthest right

4. Examples Find the slope that passes through the following points.
(0,6) and (5,2)
(-3,0) and (4,7)

5. Find the slope of these two lines

6. Postulate 17: SLOPES OF PARALLEL LINES
In a coordinate plane, two nonvertical lines are parallel if and only if they have the same slope. Any two vertical lines are parallel

7. Example
Line p passes through (0, -3) and (1, -2). Line m passes through (5,4) and (-4, -4). Line n passes through (-6, -1) and (3, 7). Find the slope of each line. Which lines are parallel?

8. Slope-Intercept Form
The y-intercept is the y-coordinate of the point where the line crosses the y-axis.

9. Writing an Equation of a Line
Write an equation for the following lines with the given information.
Passes through (2,3) and has a slope of 5.
Passes through (4,9) and has a slope of -2.
Passes through (20,5) and has a slope of 3/10.

10. Writing an Equation of a Parallel Line
Line n has the equation y = (-1/3)x – 1. Line m is parallel to n and passes through the point (3,2). Write an equation of line m.

11. Example
Line a has the equation y = (2/5)x + 3. Line b is parallel to a and passes through the point (-5,0). Write an equation for line b.