AMC 8 1986 Problem 13
AMC8 1986 年第 13 题
面积与周长（综合）★★★☆☆
The perimeter of the polygon shown is
所示多边形的周长是
- A.14
- B.20
- C.28
- D.48
- E. / 无法由所给信息确定
正确答案 · Correct Answer
C
解析 · Solution
Solution 1
The unlabeled vertical sides must have total length 6 while the unlabeled horizontal sides must have total length 8. Thus the unlabeled sides have total length 14, so the total perimeter is 14 + 6 + 8 = 28.
Extend two unlabeled sides of the original figure form a 6×8 rectangle, as shown. Notice that the extensions added to these two sides are the same lengths as the other two unlabeled sides of the original figure, so the 6×8 rectangle has the same perimeter as the original figure. Therefore, the perimeter of the original figure is 2(6+8) = 28.
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