Posted by Lily on .
Find the equation of the perpendicular bisector of the line segment joining the points (1, 2) and (2, 1)
Does it mean I have to find the line. Then find a line that cuts that line in to half because perpendicular bisector

Math 
Steve,
just find the slope of the line: 1/3
the perp has slope 3, so now we have a midpoint (1/2,3/2) and a slope (3), and our line is
y  3/2 = 3(x + 1/2) 
Math 
Lily,
So the equation is 3(x+1/2)?
Like there's no Y= in it? 
Math 
Steve,
I gave you the equation. There's always a y. If you want it it slopeintercept form, which most people find comforting, that would be
y = 3x
Visit
http://rechneronline.de/functiongraphs/
and plot the two functions
(x+5)/3 and 3x
and you will see that the two lines intersect midway between the two given points