Question 61050
could the following lengths form a trinagle?  yes or no     
1.)   7,5,2       
2.)   9,12,13         
3.)     12,2,19 

In a triangle the sum of any two sides must be greater than the third side.

1.) 2+5 is not greater than 7 so not a triangle.
2.) 9+12 > 13. 9+13 > 12. 12+3 > 9. Yes, it's a triangle.
3.) 12+2 is not greater than 9 so not a triangle.