AMC8 1992

AMC8 1992 · Q10

AMC8 1992 · Q10. It mainly tests Triangles (properties), Area & perimeter.

An isosceles right triangle with legs of length 8 is partitioned into 16 congruent triangles as shown. The shaded area is

一个腿长为 8 的等腰直角三角形被分割成 16 个全等的三角形，如图所示。阴影部分的面积是

(A) 10 10

(B) 20 20

(D) 40 40

(E) 64 64

Answer

Correct choice: (B)

正确答案：（B）

Solution

Answer (B): The area of each of the small shaded triangles is $\frac{1}{2}\times 2\times 2=2$. There are ten of these, so the shaded area is $2\times 10=20$.

答案（B）：每个小的阴影三角形的面积是 $\frac{1}{2}\times 2\times 2=2$。这样的三角形有 10 个，所以阴影部分的面积是 $2\times 10=20$。

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