Euler's Circles
The circumcenter is found at the intersection of a triangle's three sides' perpendicular bisectors.
The orthocenter is found at the intersection of the three lines formed by connecting a perpendicular to its opposite angle's vertex.
The centroid is found by connecting the midpoints to their opposite vertices.
Create any triangle and use the Orthocenter, Circumcenter, and Centroid tools to find the various centers of a triangle. Move the corners of the triangle and observe how the centers move.