Question 94766This question is from textbook Algerbra 2
: Decide wether the lines ae parallel, perpendicular, or neither
34. Line 1 contains (4,-4) and (-16, 1)
Line 2 contains (1, 5)and(5, 21)
This question is from textbook Algerbra 2
Answer by Edwin McCravy(20060)   (Show Source):
You can put this solution on YOUR website!
Decide wether the lines ae parallel, perpendicular, or neither
34. Line 1 contains (4,-4) and (-16, 1)
Line 2 contains (1, 5)and(5, 21)
Draw them and see how they look:
They look perpendicular, so let's find their slopes and see
if one is the reciprocal of the other with the opposite sign.
Slope formula
y2 - y1
m = ---------
x2 - x1
For line 1, (x1,y1) = (4,-4) and (x2,y2) = (-16, 1)
(1) - (-4) 1 + 4 5
m = ------------- = --------- = ----- = 
(-16) - (4) -16 - 4 -20
For line 2, (x1,y1) = (1, 5) and (x2,y2) = (5, 21)
(21) - (5) 16
m = ------------- = --------- =  or 
(5) - (1) 4
Yes, and + are reciprocals of each other
but with the opposite sign. So they are perpendicular.
Edwin
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