GRE考试

【单选题】Life expectancy among adults 45 and 65 years of age by family income, sex, and race: United States, average annual 1979-89




In the figure above, the diameter of the circle is 20 and the area of the shaded region is 80π. What is the value of a + b + c + d
网考网参考答案：E
网考网解析：
Since the diameter of the circle is 20, the radius is 10 and the area is 100π. Since the area of the shaded region is 80π, it is [*] of the circle, and the white area is [*] of the circle. So the sum of the measures of the two white central angles is [*] of 360°, or 72°! The sum of the measures of all six angles in the triangles is 360°, so a + b + c + d= 360 -72 = 288. document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>