Orthogonal Vectors for Sphere Construction: Find Center and Radius

[nameVoid]

R <x,y,z>
A<a1,a2,a3>
B<b1,b2,b3>

Show that (r-a).(r-b)=0 represents a sphere find its center and radius

So i see that if 2 vectors are orthogonal you can create a sphere and find the radius and center but can someone better explain this problem

 

[LCKurtz]

What is there to explain? Write out the equations and put them in standard form to identify it. Geometrically, you may recall that an angle inscribed in a semicircle is a right angle. This is the 3D analogue of that.