Triangular pyramid from rectangular paper

Some rectangular pasteboard is cut off along a diagonal line, as shown in Fig. 1.

By using this I would like to make the glass which has the form of the triangular pyramid as shown in Fig. 2.

However, it may be unable to make or able to make depending on the length of the side AB.

Answer the conditions of the length of the side AB in the case of being able to make.

Answer