What is the significance of the geometric pattern on the book cover?
The triangles and squares on the cover are inspired by the ancient “husan-thu” (proof-without-words) proof of the Pythagorean theorem from China. The theorem states (roughly) that “the square of the hypotenuse of a right-angled triangle equals the sum of the squares of the other two sides.” The orange triangles are right-angled triangles. The areas in the dark squares are the “squares” of the various sides of this triangle. Note that the area in the light blue rectangles equals twice the area in one orange triangle. Also note that the pattern consists of four larger squares containing either 4 orange triangles and the square of the hypothenuse or 2 light blue rectangles and the squares of the other two sides. Taking away the area in the four triangles and the equal area in the two blue rectangles shows that the area in the square of the hypotenuse equals the sum of the areas in the squares of the other two sides. This pattern seemed appropriate for the cover because the Pythagorean the
