2. If vector GA+ vector GB+ vector GC=0 vector, then G is the center of gravity of ⊿ABC.

3, if the vector HA? Vector HB = vector HB? Vector HC = vector HC? Vector HA, then h is the center of ⊿ABC.

4. If a vector IA+b vector IB+c vector IC=0 vector, then I is the heart of ⊿ABC.

5. if a vector PA=b vector PB+c vector PC=0 vector, then p is the centroid of angle a.