1. CONCEPT: WRITING EQUATIONS OF LINES EQ: HOW DO WE WRITE THE EQUATION OF A LINE THAT IS PARALLEL OR PERPENDICULAR TO A GIVEN LINE? (G.GPE.5) VOCABULARY : SLOPE, PARALLEL, PERPENDICULAR, RECIPROCAL LESSON 6.1B WRITING EQUATIONS OF PARALLEL AND PERPENDICULAR LINES

2. FIRST WORD Create an acrostic about everything you remember from the previous lesson using the word. S L O P E

3. INTRODUCTION Parallel lines are lines which never touch or intersect. Perpendicular lines are lines which meet or intersect and create a 90° angle aka a right angle. We can find the equation of two lines which are parallel or perpendicular and prove whether the lines are parallel or perpendicular.

4. PARALLEL LINES

5. EXAMPLE 1

6. EXAMPLE 2

7. YOU TRY 1

8. YOU TRY 2

9. EXAMPLE 3 1. State the point-slope formula. 3. Substitute the values into the formula. 4. Simplify into slope-intercept form.

10. EXAMPLE 4 Using the graph to the right, find the equation of a parallel line which passes through the point which is not on the given line. 1. Find the slope of the given line. 3. Substitute the values into the point-slope formula. 4. Simplify into slope-intercept form.

11. YOU TRY 3 1. State the point-slope formula. 3. Substitute the values into the formula. 4. Simplify into slope-intercept form.

12. PERPENDICULAR LINES

13. EXAMPLE 5

14. EXAMPLE 6

15. YOU TRY 4

16. YOU TRY 5 Are these lines perpendicular? Explain

17. EXAMPLE 7 1. State the point-slope formula. 3. Substitute the values into the formula. Use the new slope you found for m. 4. Simplify into slope-intercept form.

18. EXAMPLE 8 Using the graph to the right, find the equation of a parallel line which passes through the point which is not on the given line. 1. Find the slope of the given line. 3. Substitute the values into the point-slope formula. Use the new slope you found for m. 4. Simplify into slope-intercept form.

19. YOU TRY 6 1. State the point-slope formula. 3. Substitute the values into the formula. Use the new slope you found for m. 4. Simplify into slope-intercept form.

20. 3-2-1 List three important facts you learned about today. List two concepts you already knew. List one task you still need to work on.