Integral Isosceles Triangle-Parallelogram and Heron triangle-Rhombus Pairs with a Common Area and Common Perimeter Das, P.; Juyal, A.; Moody, D. Journal of Number Theory 180: 208-218 2017 0022-314X 10.1016/j.jnt.2017.04.009 https://eurekamag.com/research/059/868/059868888.php