1. Warm Up Solve each equation for y. 1. y – 6x = 92. 4x – 2y = 8 2.9A Parallel and Perpendicular Lines

2. Objectives Graph lines and write their equations in slope-intercept and point-slope form. Classify lines as parallel, intersecting, or coinciding. 2.9A Parallel and Perpendicular Lines

3. Parallel LinesPerpendicular LinesIntersecting Lines Relationship Same slope & different y-intercept Slopes are opposite reciprocals Different slopes Example Pairs of Lines

4. Decide whether the lines are parallel, perpendicular, or neither. ** You will sometimes need to first: solve the equations for y, and then: identify the slopes to answer the problem. Example 1: y = 3x + 7 y = –3x – 4

5. Example 2:

6. 2y – 4x = 16 y – 10 = 2(x - 1) Example 3:

7. 3x + 5y = 2 3x + 6 = -5y Example 4:

8. 2y = 4x + 124x – 2y = 8 Example 5:

9. 3x + 5y = 2 State what the slope would be for a parallel line and for a perpendicular line to the given line. ** You may need to first solve the equation for y in order to identify the slope. Example 6:

10. y – 5 = 2(x + 3) Example 7:

11. 3x + 6 = -5y Example 8:

13. Find the slope and the y-intercept of each line to write the equation of the line in slope-intercept form. Example 9: