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### Sphere Equation Variables

```
Date: 08/21/2001 at 21:19:06
From: Timmy
Subject: Calculus

I'm a bit unfamiliar with the equation for a sphere and what all the
the variables represent. In the standard equation:

r^2 = (x-h)^2 + (y-K0^2 + (z-l)^2

...what do the points h, k, and l represent?  I'm just trying to get
a basis for better understanding what the numbers I'm plugging in
actually mean.

```

```
Date: 08/22/2001 at 13:40:18
From: Doctor Ian
Subject: Re: Calculus

Hi Timmy,

Go to one corner of a room.  The lines where the walls and the floor
intersect are the axes of a three-dimensional coordinate system:

z
|
|
|
+----------- y
/
/
/
x

Move h units along the x-axis; then move k units parallel to the
y-axis; then move l (lowercase 'L') units parallel to the z axis.
This is the center of the sphere; and r is the radius of the sphere.

If you change the values of h, k, and l, the sphere moves around, but
stays the same size.  If you change the value of r, the sphere grows
or shrinks.

Does this help?

- Doctor Ian, The Math Forum
http://mathforum.org/dr.math/
```
Associated Topics:
High School Geometry
High School Higher-Dimensional Geometry

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