Piyush Theorem. https://piyushtheorem.wordpress.com/2017/02/08/a-new-theorem-introduced-by-piyush-goel-with-four-proofs/amp/#aoh=15686179130789&referrer=https%3A%2F%2Fwww.google.com&_tf=From%20%251%24s Piyush Theorem.