The problem is this: A set S consists of triangles whose sides have integer lengths less than 5, and no two elements of S are congruent or similar. What is the largest number of elements that S can have?
I got an answer of 9, but the solution on aops says: "Based on the wording of Problem 13 to specifically exclude triangles with zero area: "... triangle with positive area ...", the definition of a triangle in this test includes degenerate ones. That is, the triangle inequality is not strict."
They are then able to find three degenerate triangles, changing the answer to 12 which is also an answer choice. Can degenerate triangles be assumed to count as triangles in this way? Shouldn't they specify within the problem?