The perpendicular bisectors of the three sides of an acute triangle intersect each other
Inside the triangle
Circumcentre is the centre of the circumcircle of a triangle.
If the triangle is
(a) An acute-angled triangle, then the circumcentre of the triangle lies inside the triangle.
(b) A right-angled triangle, then the circumcentre of the triangle lies on the hypotenuse of the triangle and it bisects the hypotenuse, i.e., the midpoint of the hypotenuse.
(c) An obtuse-angled triangle, then the circumcentre of its circumcircle lies on the outside of the triangle.