AMC8 2001

AMC8 2001 · Q9

AMC8 2001 · Q9. It mainly tests Fractions, Area & perimeter.

The large kite is covered with gold foil. The foil is cut from a rectangular piece that just covers the entire grid. How many square inches of waste material are cut off from the four corners?

大风筝覆盖着金箔。箔是从刚好覆盖整个网格的矩形片裁剪的。从四个角切掉的废料有多少平方英寸？

(A) 63 63

(B) 72 72

(D) 189 189

(E) 264 264

Answer

Correct choice: (D)

正确答案：（D）

Solution

(D) The upper corners can be arranged to form a $6 \times 9$ rectangle and the lower corners can be arranged to form a $15 \times 9$ rectangle. The total area is $54 + 135 = 189$ square inches. (Note that the kite’s area is also 189 square inches.)

（D）上方的角可以重新排列组成一个 $6 \times 9$ 的长方形，下方的角可以重新排列组成一个 $15 \times 9$ 的长方形。总面积为 $54 + 135 = 189$ 平方英寸。（注意：风筝的面积也是 189 平方英寸。）

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