1. PARALLEL AND PERPENDICULAR LINES

2. What is the slope and the y-intercept of the graph: y + 4x = -5 Write the equation of a line using the points: (-2, -4) and (2, 8). A bird is flying at a height of 240 ft. and slowly descending at a rate of 75 ft. per second. This is represented by the equation y = 240 – 75x. What do the slope and the y-intercept represent?

3. PARALLEL AND PERPENDICULAR LINES IN THE REAL WORLD

4. In your group, you will work to complete the first part of today’s inquiry lesson (1 – 3): Discovering Parallel Lines. You will have about 10 minutes to complete this part. What do you notice about the lines you have drawn? What do you notice about the equations of the lines? Draw a conclusion that summarizes what you have observed. Use complete sentences.

5. Parallel lines

6. PARALLEL LINES Line 1: y = 2x + 1 These two lines are parallel because they have the same slope. No matter how far they continue on, they will NEVER cross each other! Line 2: y = 2x - 3

8. Now, complete the second section of your worksheet (7 – 12): Discovering Perpendicular Lines. You will have about 10 minutes. Be ready to articulate your ideas with the rest of the class. What do you notice about the intersection of each pair of lines? Find a pattern in the pairs of slopes for each set of lines. Draw a conclusion that summarizes what you have observed.

9. PERPENDICULAR LINES

10. The red line is the graph of y = – 2x + 5 and the blue line is the graph of y = 1 / 2 x +4 These two lines are perpendicular because they have negative reciprocal slopes. They intersect at right angles.

12. PARALLEL AND PERPENDICULAR LINES Parallel lines have the SAME slope. Perpendicular lines have an OPPOSITE, RECIPROCAL slope. https://www.youtube.com/watch?v=vnnwfcDcNlY

13. To determine whether lines are parallel or perpendicular... 1.Write the equation in the from y = mx + b (slope intercept form) 2.Look at the slopes of the lines. If the slopes are the same, the lines are parallel. If the slopes are the negative reciprocals, then the lines are perpendicular.

14. Are these equations parallel or perpendicular? On your index card, record your answer. Turn this in before you leave the room.

15. 1.In a few sentences, describe the difference between a parallel line and a perpendicular line. 2.Give an example of parallel lines and perpendicular lines in the real world. 3.Say if the following are parallel, perpendicular or neither: a.y = 7x + 2 and x + 7y = 8 b.y = 2x – 5 and y = 5x - 5

16. Tonight for homework you will start working on your review sheet for the upcoming test. Use your notes and the power points on my wiki to help. Use the videos on the Homework Help slides if you need to see something visual.

17. Homework Help https://www.youtube.com/watch?v=R ew54K6mYUo https://www.youtube.com/watch?v =SgJDyIs9b2A https://www.youtube.com/watch? v=09ZpC614laQ