Question

Which expression proves that this triangle is impossible?
http://gyazo.com/b67d32a845e8d1d6d4b2886621ee849f

Answer 1

Let's say you lined up the segments of 6 and 5 units end to end (and they lined up perfectly). Their sum would be 6+5 = 11, which is 1 short of 12.


So because 5 + 6 < 12, this means that this triangle is NOT possible.


In general, if you have 3 lengths a, b, c, then a triangle is possible only if


a + b > c


this has to be true for all combinations of the lengths.