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| Question 1124693:  Find the equation of the perpendicular bisector of the segment AB, if A(1, �2.5) and B(5, 5.5). If the perpendicular bisector of AB intercepts the y-axis at point P, what are the lengths of PA and PB?
 
 Answer by mananth(16946)
      (Show Source): 
You can put this solution on YOUR website!  A(1, -2.5) and B(5, 5.5) by mid point formula
 {(x,y) = (x1+x2)/2 , (y1+y2)/2)
 (1+5)/2 , (-2.5+5.5)/2
 mid point of AB  (3,1.5)
 Find the slope of AB
 m = (y1-y2)/(x1-x2)
 (-2.5-5.5)/(1-5)
 =2
 Find the equation of perpendicular to AB
 The slope of perpendicular line will bw negative reciprocal of AB = -1/2
 Equation of perpendicular line
 slope = (-1/2) passing through (3.1.5)
 equation
 y-y1- m(x-x1)
 y-1.5) = (-1/2) (x-3)
 2y-3= -x+3
 2y+x = 6
 y= 3-(x/2)  equation of perpendicular line to AB
 
 The line intersects at (0,y)
 Plug x=0
 y=3
 The intersection point on y axis M(0,3) & B
 Distance From (0,3) to B, (5,5.5)
 Use distance formula
 OM = sqrt((5.5-3)^2+(5-0)^2)
 = 5.9
 Both distances are equal
 
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