Circumcenter of a triangle
The circumcenter of a triangle is created by the point of concurrency of triangle sides' perpendicular bisectors
 this circumcenter is the center of the circle that can be drawn with the all of the vertices of the triangle on the circumference of the circle
Link to www.mathopenref.com 
This is a link to a website that allows you to investigate the properties related to a triangle and its sides' perpendicular bisectors
