Question

大风筝要覆盖金箔。金箔从一张刚好覆盖整个方格的长方形纸上裁出。从四个角裁掉的废料有多少平方英寸？

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?

$63$

$72$

$180$

$189$

$264$

答案：D

知识点：长度、面积与体积的缩放关系面积筝形

难度评级：1020

解答：

整个方格的面积是由风筝面积公式，风筝面积是这个面积的一半，所以废料面积为 $378 \div 2 = 189$ 。 $3 \cdot 7 \cdot 3 \cdot 6 = 378.$

所以正确答案是 D。

The area of the entire grid would be $3 \cdot 7 \cdot 3 \cdot 6 = 378.$ The area of the kite is one-half this area from the formula for the area of the kite, so the wasted material is $378 \div 2 = 189.$

Thus, D is the correct answer.

2001 AMC 8 第 9 题

答案：D

难度评级：1020

解答：

其他年份的第 9 题