How you calculate this is this:
So, any two given sides much be greater than the other side.
7. The answer is no. 1 plus 5 is 6 right? 6 is less than 11, so it can never be a triangle.
8. The answer is yes. 3 plus 6 is greater than 7. 3 plus 7 is greater than 6. 6 plus 7 is greater than 3.
9. The answer is yes. 9 plus 11 is greater than 12. 9 plus 12 is greater than 11. 11 plus 12 is greater than 9.
