3/3/2010
AIM: SWBAT determine if 2 lines are parallel, perpendicular, or neither
DO NOW:
Find the slope of the line which goes through (6, ­4) and (2, ­8).
HW:
P.365# 3­11(parts c & d only)
P.369# 23­26
Mar 1­9:41 AM
1
STANDARD FORM: PARALLEL and PERPENDICULAR LINES
If two lines are PARALLEL:
­SLOPES are EQUAL!!!
Ex: Are the following pair of lines parallel?
y = 2x + 4
y = 2x ­ 1 If two lines are PERPENDICULAR:
­SLOPES are NEGATIVE RECIPROCALS
Ex:
y = ½ x + 3
y = ­2x ­ 5 What if the pair of equations look like this:
2y + 6x = 12
3y + x = 10
How do we find out if Parallel, Perpendicular, or Neither??
Steps:
1) Put in standard form: y = mx + b
2) Look at the SLOPES (ignore the y­intercept)
Determine if each of the following pairs of lines are Parallel, Perpendicular, or Neither:
1) y = ¾ x + 5
y = ­4 x ­ 1
3
2) y = 4x + 2
y = 4x ­ 9 3) y ­ 5x = 2
y + 4 = 5x
4) 3y = ­2x + 3
y ­ 3x = 5
5) 4y + 8x = 12
­6y = 12x + 18
6) 6x ­ y = 1
y + 6x = ­ 3
Apr 7­8:32 AM
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