Question

一条街的两侧路缘平行，相距 $40$ 英尺。一条由两条平行条纹围成的人行横道斜穿过街道。两条条纹在路缘上截出的长度为 $15$ 英尺，每条条纹长 $50$ 英尺。求两条条纹之间的距离，单位为英尺。

A street has parallel curbs $40$ feet apart. A crosswalk bounded by two parallel stripes crosses the street at an angle. The length of the curb between the stripes is $15$ feet and each stripe is $50$ feet long. Find the distance, in feet, between the stripes.

$9$

$10$

$12$

$15$

$25$

答案：C

知识点：平行四边形面积

难度评级：1410

解答：

人行横道是一个平行四边形。以路缘上的 $15$ 英尺为底、街道宽 $40$ 英尺为高，其面积为 $15\cdot40=600$ 。

以一条 $50$ 英尺的条纹为底，面积等于 $50$ 乘以两条条纹之间的距离 $d$ ，所以 $d=600/50=12$ 。

所以正确答案是 C。

The crosswalk is a parallelogram. Using the curb ( $15$ ft) as base and the street width ( $40$ ft) as height, its area is $15\cdot40=600$ square feet.

Using a stripe ( $50$ ft) as base, the area equals $50$ times the distance $d$ between the stripes, so $d=600/50=12.$

Thus, the correct answer is C.

2001 AMC 10 第 15 题

答案：C

难度评级：1410

解答：

其他年份的第 15 题