SOLUTION: Find the slope of the lines that pass Through each pair of the points and determine whether the lines are parallel or perpendicular.

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Question 1155600: Find the slope of the lines that pass Through each pair of the points and determine whether the lines are parallel or perpendicular. (-1,3) and (5,1). (-2,3) and (0,9).
Found 2 solutions by josgarithmetic, josmiceli:
Answer by josgarithmetic(39630) About Me  (Show Source):
You can put this solution on YOUR website!
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(-1,3) and (5,1).                                                                                                                                            (-2,3) and (0,9).

THESE!
(-1,3) and (5,1);   (-2,3) and (0,9).

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First line's slope
%281-3%29%2F%285-%28-1%29%29
-2%2F6
-1%2F3

Second line's slope
%289-3%29%2F%280-%28-2%29%29
6%2F2
3

Are the two slopes equal?
Are the two slopes negative reciprocals of eachother?

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
slope = [ change in y ] / [ change in x ]
( -1,3 )
( 5,1 )
+m%5B1%5D+=+%28+1+-+3+%29+%2F+%28+5+-%28-1%29+%29+
+m%5B1%5D+=+%28+-2+%29+%2F+6+
+m%5B1%5D+=+-1%2F3+
--------------------------------
( -2,3 )
( 0,9 )
+m%5B2%5D+=+%28+9+-+3+%29+%2F+%28+0+-%28-2%29+%29+
+m%5B2%5D+=+6+%2F+2+
+m%5B2%5D+=+3+
-----------------------
These lines are perpendicular, since
+m%5B2%5D+=+-1+%2F+m%5B1%5D+
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check:
+3+=+-1%2F%28+-1%2F3+%29+
+3+=+%28-1%29%2A%28-3%29+
+3+=+3+
OK