AMC 8 2018 Problem 23

AMC8 2018 年第 23 题

概率★★★★☆

From a regular octagon, a triangle is formed by connecting three randomly chosen vertices of the octagon. What is the probability that at least one of the sides of the triangle is also a side of the octagon?

如下图所示的正八边形中，从 8 个顶点中任选 3 个并连接起来形成一个三角形。那么这个三角形至少有一条边也是八边形的一条边的概率是多少？

AMC 8 2018 Problem 23 figure

A. $\displaystyle \frac{2}{7}$
B. $\displaystyle \frac{5}{42}$
C. $\displaystyle \frac{11}{14}$
D. $\displaystyle \frac{5}{7}$
E. $\displaystyle \frac{6}{7}$

正确答案 · Correct Answer

D

解析 · Solution

解析整理中

继续练习

免费刷 2018 整卷 →登录解锁诊断（看你哪儿弱）→