1. Parallel and Perpendicular Lines

2. Parallel Lines Slope is the same y-intercept is different

3. Examples y = 3x + 2 and y = 3x – 8 are parallel because: The slopes are the same (3); and The y-intercepts are different (2 and –8) y = 2x + 4 and 4x – 2y = 6 are parallel because: The slopes are the same (2); and The y-intercepts are different (4 and –3)

4. What is the slope that is parallel to each? y = 1/3x + 2 2x + 4y = 8 2x + 3y = 6 4x – 3y = -12 1/3 -1/2 -2/3 4/3

5. Perpendicular Lines The y-intercept does not matter The slopes must be opposite inverses of each other Flip the slope AND AND Change the sign.

6. More Examples

7. What is the slope that is perpendicular to each? y = 1/3x + 2 2x + 4y = 8 2x + 3y = 6 4x – 3y = -12 -3 2 3/2 -3/4

8. Try these- Write the equation of a line that is parallel to y = 2x + 8. y = 2 x + ___ Write an equation of a line that is perpendicular to y = 2x + 8. y = -1/2 x + __ Write an equation of a line that is parallel to 4x + 3y = 18 y = - 4/3 x + ___