For objects with uniform mass distribution, the position of the center of gravity is only related to the shape of the object. For objects with regular shapes, the center of gravity is on the geometric center of gravity. For example, the center of a uniform thin straight rod is at the midpoint of the rod, the center of gravity of a uniform sphere is at the center of the sphere, and the center of gravity of a uniform cylinder is at the midpoint of the shaft. The center of gravity of irregular objects can be determined by hanging method. The center of gravity of an object is not necessarily on the object.

The intersection of three heights of a triangle is called the vertical center of the triangle.

The point where the center of gravity, vertical center, outer center and inner center of a regular triangle coincide is called the center.

The epicenter is the intersection of the perpendicular bisector of the three sides of the triangle, which is the center of the circumscribed circle.

The heart is the intersection of bisectors of three internal angles of a triangle, that is, the center of the inscribed circle.