
 
compute the squared radius of the circle passing through the points
p, q, and r.
 

 
compute the squared radius of the smallest circle passing through p, and q, i.e. one fourth of the squared distance between p and q.  

 
compute the squared radius of the smallest circle passing through p, i.e. 0.  

 
compute the squared radius of the sphere passing through the points p,
q, r and s.
 

 
compute the squared radius of the sphere passing through the points p, q, and r and whose center is in the same plane as those three points.  

 
compute the squared radius of the smallest circle passing through p, and q, i.e. one fourth of the squared distance between p and q.  

 
compute the squared radius of the smallest circle passing through p, i.e. 0. 