# Wich three lengths could be the lengths of the sides of a triangle

In order for a triangle to actually be a triangle, the sums of 2 sides has to be greater than the 3rd side.  In the first option, 10+15 > 24, 15+24 > 10, and 10+24 > 15 so this is a triangle.  In the second option, 9+22 > 11, 22+11 > 9, but 9 + 11 is only 21, so this is not a triangle.  Option 3: 12+5=17, which, although is not greater than 17 it is the same which would make this an isosceles triangle, which is a triangle, as long as 12+17 > 5 and 5+17 > 12, which of course they are.  In the last option: 7+6 is only 13 which is not greater than 21, so the last one is not an option either.  Only the first and the third.

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