English: Generalisation of Pythagoras's theorem to scalene triangle. A double headed arrow joins intersection of lines parallel to sides to the corner of the triangle. This vector forms the two sides of the bottom parallelogram. The blue area is the same as the sum of the green areas, as shown by George Jennings (1997) "Figure 1.32: The generalized Pythagorean theorem" in Modern geometry with applications: with 150 figures (thứ 3 ed.), Springer, p. 23 ISBN: 038794222X.