Find an equation for the perpendicular bisector of the line segment whose endpoints are (6,9) and (2,5).
1 answer:
Answer:
x + y = 11
Step-by-step explanation:
The perpendicular bisector goes through the midpoint of the segment and has a slope that is the opposite reciprocal of the slope of the segment. The midpoint is ...
M = (A+B)/2 = ((6, 9) +(2, 5))/2 = (6+2, 9+5)/2 = (8, 14)/2
M = (4, 7) = (Mx, My)
The slope can be found from the differences of the coordinates of the two points:
(Δx, Δy) = (2 -6, 5 -9) = (-4, -4)
Factoring out -4, this becomes
(Δx, Δy) = (1, 1)
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These values can be used directly to form the equation of the perpendicular line:
(Δx)(x -Mx) +(Δy)(y -My) = 0
1(x -4) +1(y -7) = 0
x + y = 11 . . . . . . . . . add 11 and simplify
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<em>Additional comment</em>
Using "standard form" for the equation, we don't actually need the value of the slope. If you were to use point-slope form or slope-intercept form for the equation of the line, then you would need to know the slope of the segment is ...
m = Δy/Δx = 1/1 = 1
and the slope of the perpendicular is ...
m' = -1/m = -1/1 = -1
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To read more about perpendicular bisectors, see ...
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