The Word Pyramid

[Taken from Mensa: 12.]

Place the letters shown into the diagram in such a way that three words can be read across and one down the middle. What are the words? Explain your strategy for answering this problem. Where did you begin?

A A D D I I I L L L Q T U V W Y

                             __

                          __ __ __

                       __ __ __ __ __

                    __ __ __ __ __ __ __