A right triangle is called rational when its legs and hypotenuse are all rational numbers.
Examples of rational right triangles include Pythagorean triples like (3; 4; 5). We can scale
such triples to get other rational right triangles, like (3=2; 2; 5=2). Of course, usually when
two sides are rational the third side is not rational, such as the (1; 1;p2) right triangle.
Any rational right triangle has a rational area, but not all (positive) rational numbers
can occur as the area of a rational right triangle. For instance, no rational right triangle has
area 1. This was proved by Fermat. The question we will examine here is: which rational
numbers occur as the area of a rational right triangle?