A point equidistant from 3 points will be the circumcentre of the triangle with these points as vertices.

                                                                                                 _  _        _

Vectorial representation of circumcentre of triangle whose p.v's are  a, b and c

will be

           _  _       _  _      _  _  

           Ir-aI  =   Ir-bI  =   Ir-cI 

 

Is it right??????????????????????????????????????????????????????????