题干
【问题引入】
已知：如图BE、CF是ΔABC的中线，BE、CF相交于G。求证：
=
=
| G |
| E |
| G |
| B |
| G |
| F |
| G |
| C |
| 1 |
| 2 |
证明：连结EF
∵E、F分别是AC、AB的中点
∴EF∥BC且EF＝ 60
BC
| × |
| π |
| × |
| 6 |
∴
=
=
=
| G |
| E |
| G |
| B |
| G |
| F |
| G |
| C |
| E |
| F |
| B |
| C |
| 1 |
| 2 |
