选择题
2018 AMC 8 Problem 23: Octagon Triangle Probability
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 side of the triangle is also a side of the octagon?
2018 AMC 8 第 23 题：八边形三角形概率
从正八边形开始，通过连接八边形的三个随机选择的顶点形成三角形。三角形的至少一条边也是八边形的一条边的概率是多少
A.
2/7
B.
5/42
C.
11/14
D.
5/7
E.
6/7