#1

I have a homework problem but I have no idea what to do on it. It says:

Write the equation of the

I know that a perpendicular bisector is "The line perpendicular to a segment passing through the segment's midpoint." All I need to know now is how to find it.

Write the equation of the

__perpendicular bisector__of AB: A=(3,8) B=(7,6)I know that a perpendicular bisector is "The line perpendicular to a segment passing through the segment's midpoint." All I need to know now is how to find it.

#2

Okay, gradient of the line AB;

m = deltaY/deltaX

= -2/4

Sub in (3, 8)

y = mx + c

8 = (-2/4 x 3) + c

6.5 = c

y = -2/4x + 6.5

You now want the opposite line to this, so the gradient becomes 4/2 = 2

[EDITED OUT BECAUSE IT WAS WRONG]

I'm pretty tired right now, so I might have made some stupid mistakes in there.

EDIT: Wait, this could be wrong, I forgot it needs to bisect the two points. Gimme a minute...

Midpoint; (5, 7)

y = 2x + c

7 = 10 + c

c = - 3

y = 2x - 3

*shrug* Like I say, could be wrong in places, but I think it's at least on the right lines.

m = deltaY/deltaX

= -2/4

Sub in (3, 8)

y = mx + c

8 = (-2/4 x 3) + c

6.5 = c

y = -2/4x + 6.5

You now want the opposite line to this, so the gradient becomes 4/2 = 2

[EDITED OUT BECAUSE IT WAS WRONG]

I'm pretty tired right now, so I might have made some stupid mistakes in there.

EDIT: Wait, this could be wrong, I forgot it needs to bisect the two points. Gimme a minute...

Midpoint; (5, 7)

y = 2x + c

7 = 10 + c

c = - 3

y = 2x - 3

*shrug* Like I say, could be wrong in places, but I think it's at least on the right lines.

*Last edited by JamieB at Jan 18, 2007,*

#3

Find the gradient of the line it bisects. The gradient of the perpendicular bisector is -1/(the gradient of the line it bisects).

Find the midpoint of the line you're given two co-ordinates of.

Put those co-ordinates and the gradient you found into y-y1=m(x-x1) where y1 is the y value of the middle point of the line, and x1 is the x value and m is the gradient.

then re-arrange into either y=mx+c, or whatever form you want.

P.s., if some has already answered, i'm not gonna edit this post and say 'oh crap'

Find the midpoint of the line you're given two co-ordinates of.

Put those co-ordinates and the gradient you found into y-y1=m(x-x1) where y1 is the y value of the middle point of the line, and x1 is the x value and m is the gradient.

then re-arrange into either y=mx+c, or whatever form you want.

P.s., if some has already answered, i'm not gonna edit this post and say 'oh crap'

#4

Alright I worked it out and got y=2x-3

I'm not sure if that's right. I got the midpoint to be (5,7) and the slope to be -2/4 which reduces to -1/2 which ends up being 2 for the perpendicular bisector.

I'm not sure if that's right. I got the midpoint to be (5,7) and the slope to be -2/4 which reduces to -1/2 which ends up being 2 for the perpendicular bisector.

#5

do your own homework!

#6

The grad of AB is -1/2 I think, then just do the standard method. I think (5,7) is the mid point. That would mean you get y= 2x - 3? That's all in my head so who knows?

#7

Alright I worked it out and got y=2x-3

I'm not sure if that's right. I got the midpoint to be (5,7) and the slope to be -2/4 which reduces to -1/2 which ends up being 2 for the perpendicular bisector.

Yes, that'd be right.

I managed to get 6 - 8 = -1

Now I've corrected it and I get the same as you.

#8

Alright great. Thanks for all the help

#9

Alright great. Thanks for all the help

You did it all yourself.

#10

You did it all yourself.

no he didn't!

#11

no he didn't!

Yes he did!

#12

Yes he did!

why did he say, thanks for the help, you cheater helper!

#13

Yes, I know it's been answered, BUT I'm still on break, and typing these things up in paint is a nice break from reading.

That said, enjoy my educational picture.

That said, enjoy my educational picture.

#14

I saved that for future use.

#15

It's perpendicular, not parallel

#16

answer is y=2x-3

I had it all typed out but then my computer crashed

I had it all typed out but then my computer crashed