So to calculate the area of a triangle, you can work out the area of the rectangle and then divide by 2. The formula for working out the area of a right-angled triangle is: b a s e × h e i g h t 2 ...

Starting from any given rational-sided, right triangle, for example, the (3, 4, 5)-triangle with area 6, we use Euclidean geometry to show that there are infinitely many other rational-sided, right ...