Well, technically yes. One can, but it would be a so-called "degenerate triangle".
-- The 4-cm and 5-cm sides are just exactly long enough to connect between the ends of the 9-cm side. So they lie flat on top of it.
-- The angles at each end of the 9-cm side are both zero.
-- The angle at the vertex where the 4-cm side meets the 5-cm side is 180 degrees.
-- The sum of the angles in the triangle is 180 degrees.
-- The altitude of the triangle is zero.
-- The area of the triangle is zero.
-- When you look at the triangle, all you see is a 9-cm line segment. The 4-cm and 5-cm line segments lie on top of it, so you don't see them.
-- You would say "There's no triangle there.".