Which of the following sets of numbers could not represent the three sides of a triangle?
+500 By triangle inequality theorem, any two given sides, a, b, of a triangle, must be greater than or equal to the third side
a+b >= c
Just check all of the 4 cases for the answer, it will be the outlier that does not satsify the above condition. In other words, when you add two of the sides, it is smaller than the third side.
+98 Triangle Rule: The sum of the lengths of any two sides of a triangle must be greater than the third side.
1. Let's list all the sets. {8, 16, 21}{12, 17, 27}{8, 23, 31}{5, 8, 11}
2. Now is...
8+16 greater than 21?
12+17 greater than 27?
8+23 greater than 31?
5+8 greater than 11?
I'll leave that to you. 
