module’10:’ coordinate’proof’ using’slope’and’ distance · now prove that if two...
TRANSCRIPT
Understanding Slope
• Two (non-vertical) lines are parallel if and only if they have the same slope. (All vertical lines are parallel.)
8
6
4
2
-‐2
-‐4
-‐6
-‐8
-‐10 -‐5 5 10
D: (4, -1)
C: (-2, -4)
B: (3, 3)
A: (-1, 1)
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Understanding Slope
• The slope of AB is:
• The slope of CD is:
• Since m1=m2, AB || CD
8
6
4
2
-‐2
-‐4
-‐6
-‐8
-‐10 -‐5 5 10
D: (4, -1)
C: (-2, -4)
B: (3, 3)
A: (-1, 1)( )13 1 2 13 1 4 2
m −= = =
− −
( ) ( )( )2
1 4 3 14 2 6 2
m− − −
= = =− −
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