Question

Betsy 用蓝色三角形、小白色正方形和红色中心正方形设计了一面旗帜，如图所示。设 $B$ 为蓝色三角形总面积， $W$ 为白色正方形总面积， $R$ 为红色正方形面积。下列哪一项正确？

Betsy designed a flag using blue triangles, small white squares, and a red center square, as shown. Let $B$ be the total area of the blue triangles, $W$ the total area of the white squares, and $R$ the area of the red square. Which of the following is correct?

$B=W$

$W=R$

$B=R$

$3B=2R$

$2R=W$

答案：A

知识点：面积分割全等（几何）

难度评级：1270

解答：

画出网格线和对角线，把旗帜分成全等的直角三角形。数一数可得蓝色区域有 $24$ 个，白色区域有 $24$ 个，红色区域有 $16$ 个。

因此 $B=W$ 。

所以正确答案是 A。

Divide the flag into congruent right triangles by drawing the grid lines and diagonals. Counting gives $24$ triangles in the blue region, $24$ in the white region, and $16$ in the red region.

Hence $B=W.$

Thus, the correct answer is A.

2002 AMC 10A 第 8 题

答案：A

难度评级：1270

解答：

其他年份的第 8 题