在解题时 ,通过仔细观察 ,挖掘出题中数字的组合特征或分解特征 ,并由此进行分析、变换、联想、构造等 ,常可获得巧妙的解题思路 ,从而简捷地将问题解决 .下面举两例略加说明 .例 1　如图 1 ,已知 ABC的重心为M ,AM =3,BM =4,CM =5 ,那么S ABC =.分析　若注意到“3,4,5”是一 In the problem-solving, through careful observation, the combined features or decomposition features of the numbers in the questions are excavated, and from this analysis, transformation, association, construction, etc., clever problem-solving ideas can often be obtained, thereby simply solving the problem. Two examples are shown below. Example 1 As shown in Figure 1, the center of gravity of ABC is known as M, AM = 3, BM = 4, CM = 5, then S ABC =. Analysis if you notice “3,4,5” is one