Can All 4 Sided Figures Be Made From 2 Triangles?

I believe any figure, plane or not, defined by 4 points and 4 line segments joining them in some loop can be made from 2 triangles. If you have a 4-sided figure that does not meet this description, it may not be able to be made from 2 triangles. If the 4-sided figure has vertices A, B, C, and D, one of the triangles could be ABD, and the other could be BCD, for example.