Section 3.8 slopes of parallel and perpendicular lines.notebook
October 04, 2016
10/4/16 ­ Warm Up Problem
What is the slope of the line that goes through the two points?
H(­3, 4)
G(2, 6)
Graph the line that goes through points H and G.
Sep 20­12:06 PM
1
Section 3.8 slopes of parallel and perpendicular lines.notebook
October 04, 2016
Oct 4­9:37 AM
2
Section 3.8 slopes of parallel and perpendicular lines.notebook
October 04, 2016
Section 3.8 Slopes of Parallel and Perpendicular Lines
Goals: Write linear equations in slope­intercept and point­
slope form
Relate slope to parallel and perpendicular lines
What is the slope of the red line?
What is the slope of the blue line?
How would you describe how they are related?
Sep 21­9:03 AM
3
Section 3.8 slopes of parallel and perpendicular lines.notebook
October 04, 2016
Slopes of Parallel Lines
­ Two nonvertical lines are parallel if and only if they have the same slope
­ Any two vertical lines are parallel
Determine if the two lines are parallel.
(­4,4)
(6,­1)
(­3,­1)
(7,­6)
Sep 20­12:07 PM
4
Section 3.8 slopes of parallel and perpendicular lines.notebook
October 04, 2016
What is the slope of the red line?
What is the slope of the blue line?
How do the two lines appear to be related to each other?
Sep 21­9:20 AM
5
Section 3.8 slopes of parallel and perpendicular lines.notebook
October 04, 2016
Slopes of Perpendicular lines
­ Two nonvertical lines are perpendicular if and only if they have opposite reciprocal slopes.
­ Any horizontal line and vertical line are perpendicular.
Determine if the lines are perpendicular.
(2,5)
(9,4)
(­3,0)
(4,­1)
Sep 20­12:07 PM
6
Section 3.8 slopes of parallel and perpendicular lines.notebook
October 04, 2016
Writing Equations of Lines
Write the equation of the line through point P(­1,4) with a slope of 3.
Write the equation of the line parallel to the line y = ­2x + 6 that goes through point Q(1, ­7).
Write the equation of the line perpendicular to the line y = 3x ­ 7 that goes through point R(3, 5).
Sep 20­12:06 PM
7
Section 3.8 slopes of parallel and perpendicular lines.notebook
October 04, 2016
Writing Equations Given Two Points
Write an equation of the line through A(‐2,3) and B(1,‐1).
Write an equation of the line through P(5,0) and Q(7,‐3).
Sep 20­12:05 PM
8
Section 3.8 slopes of parallel and perpendicular lines.notebook
October 04, 2016
Assignment:
MathXL
3.8 Assignment
Sep 20­12:09 PM
9