1. 4.3 Parallel and Perpendicular Lines
Algebra 2/Geometry
High School

2. Parallel and Perpendicular Lines
Teacher Page
Content: Write the equation of a parallel or perpendicular line to a given line, in slope intercept form.
Grade Level: Algebra 2/Geometry
Creator: Don Sutcliffe
Other – Print slides as a handout for students to take notes.
MAP TAP
Parallel and Perpendicular Lines

3. Parallel and Perpendicular Lines
Teacher Page
Curriculum Objectives:
Algebra 2 – II.A – The learner will find the slope of a linear equation and the relationships of the slopes of parallel and perpendicular lines.
MAP Objectives:
Missouri Show-Me Standard – Math – MA1, MA2, MA4, MA5
Missouri Show-Me Standard – Goal – G1.6, G3.4, G3.5, G4.1
MAP TAP
Parallel and Perpendicular Lines

4. Parallel and Perpendicular Lines
Parallel Lines
Two non-vertical lines are parallel if and only if their slopes are equal.
If l1║l2, then m1= m2.
If m1= m2, then l1║l2. m1 m2 l1 l2
MAP TAP
Parallel and Perpendicular Lines

5. Parallel and Perpendicular Lines
Write the equation of the line that passes through (3,6) and is parallel to y = 2/3x+2.
m = 2/3 and the point is (3,6)
y = mx+b
6 = 2/3(3)+b
6 = 2+b
4 = b
y = 2/3x+4
MAP TAP
Parallel and Perpendicular Lines

6. Parallel and Perpendicular Lines
Write the equation of the line that passes through (4,-5) and is parallel to y = -2x-4.
m = -2 and the point is (4,-5)
y = mx+b
-5 = -2(4)+b
-5 = -8+b
3 = b
y = -2x+3
MAP TAP
Parallel and Perpendicular Lines

7. Parallel and Perpendicular Lines
Write the equation of the line that passes through (-6,4) and is parallel to y=1/3x-1.
m=1/3 and the point is (-6,4)
y =1/3x+6
MAP TAP
Parallel and Perpendicular Lines

8. Perpendicular Lines
Two non-vertical lines are perpendicular if and only if the product of their slopes is -1.
If l1┴l2, then m1 ● m2= -1.
If m1● m2 = -1, then l1┴l2. m1 l1 m2
Slopes are negative reciprocals l2
MAP TAP
Parallel and Perpendicular Lines

9. Parallel and Perpendicular Lines
Write the equation of the line that passes through (6,-5) and is perpendicular to y = 2x+3.
m = -1/2 and the point is (6,-5)
y = mx+b
-5 = -1/2(6)+b
-5 = -3+b
-2 = b
y = -1/2x-2
MAP TAP
Parallel and Perpendicular Lines

10. Parallel and Perpendicular Lines
Write the equation of the line that passes through (6,-7) and is perpendicular to y = 2/3x+1.
m = -3/2 and the point is (6,-7)
y = mx+b
-7 = -3/2(6)+b
-7 = -9+b
2 = b
y = -3/2x+2
MAP TAP
Parallel and Perpendicular Lines

11. Parallel and Perpendicular Lines
Write the equation of the line that passes through (-4,-3) and is perpendicular to y = x+6.
m = -1 and the point is (-4,-3)
y = -x-7
MAP TAP
Parallel and Perpendicular Lines

12. Parallel and Perpendicular Lines
End Show
MAP TAP
Parallel and Perpendicular Lines

13. Parallel and Perpendicular Lines
Parallel Lines
Two non-vertical lines are parallel if and only if their slopes are equal.
If l1║l2, then m1= m2.
If m1= m2, then l1║l2. m1 m2 l1 l2
MAP TAP
Parallel and Perpendicular Lines

14. Parallel and Perpendicular Lines
Write the equation of the line that passes through (3,6) and is parallel to y = 2/3x+2.
m = _____ and the point is (__,__)
y = mx+b
MAP TAP
Parallel and Perpendicular Lines

15. Parallel and Perpendicular Lines
Write the equation of the line that passes through (4,-5) and is parallel to y = -2x-4.
m = ____ and the point is (__,__)
MAP TAP
Parallel and Perpendicular Lines

16. Parallel and Perpendicular Lines
Write the equation of the line that passes through (-6,4) and is parallel to y=1/3x-1.
m=___ and the point is (__,__)
MAP TAP
Parallel and Perpendicular Lines

17. Parallel and Perpendicular Lines
Two non-vertical lines are perpendicular if and only if the product of their slopes is -1.
If l1┴l2, then m1 ● m2= -1.
If m1● m2 = -1, then l1┴l2. m1 l1 m2 l2
MAP TAP
Parallel and Perpendicular Lines

18. Parallel and Perpendicular Lines
Write the equation of the line that passes through (6,-5) and is perpendicular to y = 2x+3.
m = ___ and the point is (__,-__)
MAP TAP
Parallel and Perpendicular Lines

19. Parallel and Perpendicular Lines
Write the equation of the line that passes through (6,-7) and is perpendicular to y = 2/3x+1.
m = ____ and the point is (__, __)
MAP TAP
Parallel and Perpendicular Lines

20. Parallel and Perpendicular Lines
Write the equation of the line that passes through (-4,-3) and is perpendicular to y = x+6.
m = ___ and the point is (__,__)
MAP TAP
Parallel and Perpendicular Lines