Homework Help: Finding perpendicular bisector.

1. Oct 22, 2009

charlie_luna

1. The problem statement, all variables and given/known data
Point A (–4,1) is in the standard (x,y) coordinate plane. What must be the coordinates
of point B so that the line x = 2 is the perpendicular bisector of AB ?

2. Relevant equations
don't know where to start.

3. The attempt at a solution
haven't tried.

2. Oct 22, 2009

rock.freak667

Well let's start with the basics, if you know one line is the perpendicular bisector of another, what can you tell me about where the one line intersects the other line and about their gradients?

3. Oct 22, 2009

HallsofIvy

Then try! Have you drawn this on a coordinate system? Mark the point (-4,1) and the line x= 2. Notice that that is a v__________ line. Since x= 4 is to be the perpendicular to the line segment you want, draw a line from (-4, 1) perpendicular to x= 4. That will be a h__________ line. Since x= 4 bisects the line segment, you must go an equal distance on the other side of x= 2. Where do you wind up?

4. Oct 22, 2009

symbolipoint

This should be super-easy because the vertical line x=2 can only be perpendicular to a horizontal line. This problem can be solved by inspection and simple counting. Simple picture of a graph!