College of Arts and Sciences

Department of Mathematics

Although this proof was known to the ancient Chinese, it is generally associated with a twelfth century Indian mathematician, Bhaskara. He included it in his compendium of mathematical knowledge of the day, a book called the "Lilivati" (named after his daughter; for a fascinating tale about this title, see Edna Kramer's delightful book "The Mainstream of Mathematics" published by Oxford Press). His one word proof ("Behold!") is perhaps one of the earlier instances of mathematics authors leaving a great deal of development to their readers (what modern-day student has not complained of this?). Yet considering that the literate of the day were the intellectual elite, perhaps it was not too much of a stretch.