AMC 8 1995 Problem 21
AMC8 1995 年第 21 题
立体几何★★★☆☆
A plastic snap-together cube has a protruding snap on one side and receptacle holes on the other five sides as shown. What is the smallest number of these cubes that can be snapped together so that only receptacle holes are showing?
一种塑料拼插正方体，一面有凸出的插头，其余五面有凹孔，如图所示。要使拼插后只露出凹孔，最少需要多少个这样的正方体？
- A.3
- B.4
- C.5
- D.6
- E.8
正确答案 · Correct Answer
B
解析 · Solution
Solution 1
It is rather easy to see that the only way that you can possibly have three cubes without protruding snaps is to have them in a triangle formation. However, in this case, the exterior angles are , whereas the outside angle of the cubes are each. A square like formation will work in the case of 4 cubes, so the answer is .
继续练习