1. Day Problems Graph each equation.
1. y – 2 = (x – 3) 2. y + 3 = -2(x – 1)
Write an equation in point-slope form for the line through the given point with the given slope.
3. (4 , 2); m = (-5 , 2); m = 0
A line passes through the given points. Write an equation for the line in point-slope form. Then rewrite the equation in slope-intercept form.
5. (-1 , 0) , (1 , 2)

2. 6.5 Parallel and Perpendicular Lines 2/22/11
Parallel lines – lines in the same plane that never intersect.

3. Slopes of Parallel Lines
Nonvertical lines are parallel if they have the SAME SLOPE and DIFFERENT Y-INTERCEPTS. Any two vertical lines are parallel.
Example – The equations y = 2x + 1 and y = 2x + 3 have the same slope, 2, and different y-intercepts. The graphs of the two equations are parallel.

4. Determining Whether Lines are Parallel
Are the graphs of and 2x + 6y = 12 parallel? Explain.
Write 2x + 6y = 12 in slope-intercept form. Then compare with
The lines are parallel. The equations have the same slope, , and different y-intercepts.

5. Writing Equations of Parallel Lines
Write an equation for the line that contains (5 , 1) and is parallel to
Step 1 – Identify the slope of the given line.
Step 2 – Write an equation of the line through (5 , 1) using point-slope form, then change to slope-intercept.

6. Perpendicular Lines 2/23/11
Perpendicular lines – lines that intersect to form right angles.
SLOPES OF PERPENDICULAR LINES
Two lines are perpendicular their slope is the opposite reciprocal of the given slope. A vertical and horizontal line are also perpendicular.
EXAMPLE – the slope of is The slope of y = 4x + 2 is 4.

7. Opposite Reciprocal How to find the opposite reciprocal of a number:
Start with Find its Write the
a fraction reciprocal opp. reciprocal
Start with Find its Write its
an integer reciprocal opp. reciprocal

8. Writing Equations for Perpendicular Lines
Find an equation of the line that contains (0 , -2) and is perpendicular to y = 5x + 3.
Step 1- Identify the slope of the given line.
m = 5
Step 2 – Find the opposite reciprocal of the slope:
Step 3 – Use the slope-intercept form to write an equation.

9. More Practice!!! Textbook – p. 314 #2 – 30 even.
Homework – Worksheet 6.5.