选择题
2018 AMC 8 Problem 15: Shaded Circle Region
In the diagram, a diameter of each of the two smaller circles is a radius of the larger circle. If the two smaller circles have a combined area of 1 square unit, then what is the area of the shaded region, in square units?
2018 AMC 8 第 15 题：阴影圆圈区域
在图中，两个小圆各自的直径是大圆的半径。如果两个较小的圆的面积之和为 1 平方单位，则阴影区域的面积是多少（单位为平方单位）
A.
1/4
B.
1/3
C.
1/2
D.
1
E.
π/2