There are 6, you'd think there would be 8 but the answer is actually 6. A diagonal is a line segment that connects to vertices, the two vertices chosen do not count when forming the triangle, two vertices that are adjacent to that chosen vertex are NOT included when forming the diagonal. It's confusing, but I hope this helps. If you have any follow up questions I'd love to answer them.
Explanation: The probability of rolling a 2 on a 6-sided dice is 16 . The probability of rolling two 2s on two 6-sided die is, by the multiplication principle, 16×16=136 .