# Calc III

## Homework Statement

Write the equation of the sphere whose diameter has endpoints at (-1,1,-3) and (3,-1,2).

## The Attempt at a Solution

(x-x1)2+ (y-y1)2+ (z-z1)2= r2

the center of the sphere is : (1,0,-1/2)
r= $$\sqrt{}5/4$$

then the equation is: (x-1)2+(y-0)2+(z+1/2)2=5/4

Please someone check my answer and if I am not right, help me to solve it.

tiny-tim
Homework Helper
the center of the sphere is : (1,0,-1/2)
r= $$\sqrt{}5/4$$

Hi mamma_mia66!

Centre is right.

But r is wrong.

(you've calculated the distance from the centre to the origin! )

I am not sure that I know how to find the r ???? too old to remember it after so many years not being in school.

tiny-tim