AMC8 2019

AMC8 2019 · Q2

AMC8 2019 · Q2. It mainly tests Area & perimeter, Polygons.

Three identical rectangles are put together to form rectangle $ABCD$, as shown in the figure below. Given that the length of the shorter side of each of the smaller rectangles is 5 feet, what is the area in square feet of rectangle $ABCD$?

三个相同的矩形组合成矩形 $ABCD$，如图所示。已知每个小矩形的短边长为 5 英尺，矩形 $ABCD$ 的面积（平方英尺）是多少？

(A) 45 45

(B) 75 75

(D) 125 125

(E) 150 150

Answer

Correct choice: (E)

正确答案：（E）

Solution

We can see that there are $2$ rectangles lying on top of the other and that is the same as the length of one rectangle. Now we know that the shorter side is $5$, so the bigger side is $10$, if we do $5 \cdot 2 = 10$. Now we get the sides of the big rectangle being $15$ and $10$, so the area is $\boxed{\textbf{(E)}\ 150}$. ~avamarora

可以看到，有 2 个矩形上下叠放，这等于一个矩形的长度。我们知道短边是 5，所以长边是 $5 \cdot 2 = 10$。大矩形的边长为 15 和 10，面积为 $\boxed{\textbf{(E)}\ 150}$。

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