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Find the equation for the perpendicular bisector of AB A (0, 2) and B(-8, 4) is standard form

User Mohsen Sarkar
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1 Answer

15 votes
15 votes

A(0,2) and B(-8, 4)

x1 = 0; y1 = 2

x2 = -8; y2 = 4

The line that passes trhoug A and B will have this slope:

m = (y2 - y1)/(x2-x1) =(4 - 2)/(-8 - 0) = 2/-8 = -1/4 = -0.25

the equation of a line is y = mx + b

if we take the point A, this equation would be: 2 = m(0) + b

2 = b

so b = 2

the equation of the line is y = -0.25x + 2

the middle point between A and B is:

for x: (-8 - 0)/2 = -4

for y = (4 - 2)/2 = 2/2 = 1

so the middle point, the point where the bisector will pass is (-4, 1)

if the line is perpendicular, that means that its slope is -1/m of the original line

in this case -1/-0.25 = 4

if the slope is 4 and it passes throug (-4, 1), and using the equation y = mx + b with y = 1 and x = -1:

1 = 4(-1) + b

1 = -4 + b

1 + 4 = b

b = 5

so the final equation is y = 4x + 5

the answer is y = 4x + 5

User Milad Rahimi
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3.0k points