[求助]prep数学第128题，急啊

1987kevin

128

The points A, B, C, and D are on a number line, not necessarily in that order.  If the distance between A and B is 18 and the distance between C and D is 8, what is the distance between B and D ?

 

(1) The distance between C and A is the same as the distance between C and B.

 

(2) A is to the left of D on the number line.

答案是E，我觉得由两个条件能算出来啊

1987kevin

有帮忙看下的吗？谢谢

周末愉快

POSSIBLE 1: --------------A------C------B--D--------

POSSIBLE 2:---------------B------C------A--D--------

这样就没办法确定啦

1987kevin

可是第二种情况显然不可能，cd长为8， ac长为9，不可能啊

1987kevin

大牛们讲讲啊~~~

周末愉快

一样的道理啊

-----A--D---C---D--B----

再加一句话,这道题目是可以举一反三的,如果数字改变的话,要注意细节,但是方法是一样的.唠叨一句.

[此贴子已经被作者于2008-5-11 1:28:44编辑过]