If the length of two sides of a triangle are 7 and 10, the length of the third side may be

The Triangle Inequality Theorem rule states that when you add 2 sides they must be greater than the third side,

Your third side has to be less than 7+10=17

Your third side is less than 17 and greater than 3

Anything that is 17 or greater is to big

Anything that is 3 or less is to small

So your answer is between 4-16