What Is the Equation for Points Equidistant from Two Given Points in 3D Space?

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SUMMARY

The equation for the set of all points equidistant from points A(-1,5,3) and B(6,2,-2) in 3D space is derived from the midpoint and the concept of a plane. The midpoint of segment AB is calculated, and the equation of the plane that bisects the line segment perpendicularly is established. This plane represents the complete set of points equidistant from A and B, rather than a sphere, as the latter only includes points on its surface. The distance between A and B is confirmed as d=sqrt(83), leading to a radius of (sqrt(83))/2 for the sphere, but the solution requires a focus on the equidistant plane.

PREREQUISITES
  • Understanding of 3D coordinate geometry
  • Knowledge of distance formula in 3D space
  • Familiarity with the concept of midpoints
  • Basic principles of planes and perpendicular bisectors
NEXT STEPS
  • Learn how to derive the equation of a plane given two points in 3D space
  • Study the properties of perpendicular bisectors in three dimensions
  • Explore the geometric interpretation of equidistant points in 3D
  • Investigate the relationship between spheres and planes in 3D geometry
USEFUL FOR

Students studying geometry, particularly those focusing on 3D coordinate systems, as well as educators and tutors assisting with spatial reasoning and distance problems in mathematics.

fk378
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Homework Statement


Find an equation of the set of all points equidistant from the set points A(-1,5,3) and B(6,2,-2). Describe the set.


Homework Equations


d= sqrt [(x2-x1)^2 + (y2-y1)^2 + (z2-z1)^2]



The Attempt at a Solution


I solved the distance between A and B and got d=sqrt 83. If a sphere is constructed that passes through these 2 points, then the center will be equidistant from both. Therefore that sphere will have radius=(sqrt 83)/2.

I don't know where to take it from here. Any thoughts?
 
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Find the midpoint of AB.
Determine slope of AB. Determine negative reciprocal of this slope (Do you understand why?)
One or two more steps... can you do this?
 
fk378 said:

Homework Statement


Find an equation of the set of all points equidistant from the set points A(-1,5,3) and B(6,2,-2). Describe the set.

...

If a sphere is constructed that passes through these 2 points, then the center will be equidistant from both.

This is not the set the problem is asking for. It is true that the midpoint of the segment AB is equidistant from both A and B. But plainly points A and B would each have to be on the surface of that sphere you describe, yet each of those can hardly be equidistant from both.

But consider the "equator" of that sphere, where A and B are the poles. Would all of those points be equidistant from both A and B? Fill in the circle enclosed by the equator -- are all of those points equidistant from A and B? Could there be any other points in this "equidistant set"? What must the complete set be then?
 

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