1. 7.8 Parallel and Perpendicular Lines Standard 8.0: Understand the concepts of parallel and perpendicular lines and how their slopes are related.

2. Vocabulary Parallel Lines – Lines that never cross and never intersect. Perpendicular Lines – Lines that, when they cross each other, form right angles.

3. Steps for determining if graphs are parallel or perpendicular 1. Put both equations into slope-intercept form. 2. Find the slope and y-intercept of each equation. 3. Analyze the slope and y-intercept Parallel – Slope is the same; y-intercept different Perpendicular – Slope is a negative reciprocal

4. Finding Opposite Reciprocals a) -3 b) 1/3 c) -2/5 d) 6 e) -3/2 f) -1/6 g) 8 h) 3/8 i) 7/3 a) 1/3 b) -3 c) 5/2 d) -1/6 e) 2/3 f) 6 g) -1/8 h) -8/3 i) -3/7

5. #1 Determine whether the graphs of the equations are parallel lines

6. #2 Determine whether the graphs of the equations are parallel lines

7. #3 Determine whether the graphs of the equations are perpendicular lines

8. #4 Determine whether the graphs of the equations are perpendicular lines

9. #5 Write an equation for the line containing the given point and perpendicular to the given line.