# Thread: Find Coordinates of Point B

1. ## Find Coordinates of Point B

The midpoint M of line segment AB has coordinates (- 3,4). If point A is the origin, (00), what are the coordinates of point B.

MY WORK:

I used the distance formula to find the distance from point A to the midpoint. I found the distance to be 5 units from point A to the midpoint and of course, this means the distance to point B is 10 units. However, I was not able to find the coordinates of B. How do I find the coordinates of B without the need of graphing paper?

I also used the midpoint formula but got no where.

Thanks

2. Originally Posted by magentarita
The midpoint M of line segment AB has coordinates (- 3,4). If point A is the origin, (00), what are the coordinates of point B.

MY WORK:

I used the distance formula to find the distance from point A to the midpoint. I found the distance to be 5 units from point A to the midpoint and of course, this means the distance to point B is 10 units. However, I was not able to find the coordinates of B. How do I find the coordinates of B without the need of graphing paper?
hmm, ok

I also used the midpoint formula but got no where.
really?

let (x,y) be the coordinates of B. then, by the midpoint formula:

$\bigg( \frac {x + 0}2, \frac {y + 0}2\bigg) = (-3,4)$

$\Rightarrow \frac x2 = -3$ and $\frac y2 = 4$
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3. ## I see........

Originally Posted by Jhevon
hmm, ok

really?

let (x,y) be the coordinates of B. then, by the midpoint formula:

$\bigg( \frac {x + 0}2, \frac {y + 0}2\bigg) = (-3,4)$

$\Rightarrow \frac x2 = -3$ and $\frac y2 = 4$
.
.
.
I did not place x and y in the midpoint formula. This is why I was not able to find the coordinates of B.

Thanks

4. maybe im wrong but it looks like you dont need to use formula for this question. if you double the coordinates of the midpoint you should get point B (-6, 8)

then use the formula to check the answer.