mathematical problem

A: The three midlines of a triangle intersect at a point, and the distance from the point to the vertex is twice as long as the distance from the midpoint of the opposite side. (barycenter theorem), this intersection point is called the barycenter of triangle.

The perpendicular bisector of three sides of a triangle intersect at one point. This point is called the outer center of the triangle.

The three heights of a triangle intersect at a point. This point is called the vertical center of the triangle.

The bisectors of the three internal angles of a triangle intersect at one point. (Inner Theorem) This point is called the heart of a triangle.

The inner bisector of a triangle intersects with the outer bisector at the other two vertices. (Proximity Theorem) A triangle has three parameters.

Specific proof, refer to the following website:

/Article/bjzs/2005 1 1/52 . html