AMC 8 2009 Problem 7
AMC8 2009 年第 7 题
三角形★★☆☆☆
The triangular plot of ACD lies between Aspen Road, Brown Road and a railroad. Main Street runs east and west, and the railroad runs north and south. The numbers in the diagram indicate distances in miles. The width of the railroad track can be ignored. How many square miles are in the plot of land ACD?
三角形 ACD 区城处于 Aspen 公路，Brown 公路和一条铁路之间。Main 街道是东西向，铁路是南北向。图中的数字表示以英里为单位的距离。铁路轨道的宽度可以忽略。那么区域 ACD 的面积是多少平方英里？
- A.2
- B.3
- C.4.5
- D.6
- E.9
正确答案 · Correct Answer
C
解析 · Solution
Solution 1
The area of a triangle is . If we let be the base of the triangle, then the height is , and the area is .
We can see that there is a big triangle encasing . The area of that triangle is . We can easily see that triangle is , which is 4.5. 9-4.5 is 4.5, so the answer is 4.5.
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