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View Full Version : How to Find Equidistant


princessgloomy
Nov 1, 2007, 11:24 AM
Yeah I really don't know how to do this:


A point is equidistant from points A(2,1), B(2,-4), and C(-3,1). Find its coordinates.



Help! I need somebody! Not just anybody! Help! (Beatles :D )

ebaines
Nov 1, 2007, 11:34 AM
First thing is to think about what points are equidistant from A and B. Since both of these points have the same x-coordinate, all the points on the horizontal line whose y value is the average of the y values of points A and B are equidistant from both A and B. Consequently the line y= -1.5 is equidistant from both A and B. Can you see that? OK, now think about points that are equidistant from both A and C - again, these points are all on a line. Once you determine what that line is, the one point that is equidistant from A, B and C is at the intersection of the two lines. Hope this helps.

princessgloomy
Nov 1, 2007, 11:44 AM
Well the answer I got is (-1/2, -2 1/2)?

Hope it's correct. Thank you.

ebaines
Nov 1, 2007, 11:51 AM
Your x-coordinate is correct, but the y coordinate is not. Check your work. I suggest that when you think you have the answer check it by calculating the distance between that point and A,B and C to make sure the distances are all equal.