cap内建函数

这两个的答案capacity与capacity咋样得出的

var numbers3 = [5]int{1, 2, 3, 4, 5}
 slice3 := numbers3[2:len(numbers3)]   
capacity == cap(slice3)  
capacity=3

var numbers1 = [9]int{1, 2, 3, 4, 5, 5, 5, 6, 0}
var slice1 = numbers1[1:4]
var capacity1 int = cap(slice1)
capacity1=8