Triangle Inequalities

Does a triangle with these side lengths exist?
15, 12, 9

• Yes
• No
• I don't know.

Can the sides of a triangle have lengths 3, 4, and 9?

• Yes
• No

What is a possible third side to a triangle with side lengths of 13 and 4?

• 9
• 12
• 8
• 5

What is a possible third side to a triangle with side lengths of 5 and 5?

• 9
• 10
• 11
• 12

Which set of numbers may represent the lengths of the sides of a triangle?

• {2,5,9}
•  {6,6,7}
• {6,4,2}           
• {7,8,1}