#### Answer

A triangle cannot have these lengths for its sides.

#### Work Step by Step

Using the Triangle Inequality Theorem, we need to see if the sum of each of the combinations of two sides is greater than the other side:
$5 + 9 > 4$ --> This statement is true.
$4 + 9 > 5$ --> This statement is true.
$4 + 5 > 9$ --> This statement is false.
A triangle cannot have these lengths for its sides because two of the sides added together are not greater than the third side.