which set could NOT represent the lengths of the sides of a triangle ?

1) {3,4,5}
2) {5,10,12}
3) {2,5,9}
4) {7,9,11}

Question

which set could NOT represent the lengths of the sides of a triangle ?

1) {3,4,5}
2) {5,10,12}
3) {2,5,9}
4) {7,9,11}

anonymous · Answer

{2,5,9}

bibby · Answer

You can cancel the first 2 out as they're pythagorean triplets

anonymous · Answer

@cutepochacco  why

anonymous · Answer

2,5,and 9 b/c the sum of any two sides of the triangle cannot be greater than the largest side. 
so 2+5=7 
HOWEVER, 7 is less than 9 and this makes the sum of any two sides less than the largest side. 
if ur doing math A, its ok., you'll eventually get it! 
if u don't understand, just try it out with real stick

campbell_st · Answer

the sum of the shorter sides of a triangle must be greater than the length of the longest side... 

use this to find the answer

campbell_st · Answer

@cutepochacco in your example what happens if you use your rule and add 2 and 9... thats 11 and greater than the longest side