The ICTS logo is the visual proof of the right angle triangle theorem due to Bhaskara II , a 12th century Indian mathematician. See, for example Georges Ifrah, "The Universal History of Numbers, Volume 2, Penguin, India (2005)".
Legend has it that Bhaskara pointed to the figure in the logo and exclaimed “Behold”! An algebraic proof goes as follows. Take four identical right-angled triangles and arrange them as in the logo. Denote the smaller sides of any of these triangles by the symbols 'a' and 'b' with a ≤ b, and the hypotenuse by the symbol 'c'. The area of the large square is c². The side of the small square is (b – a), so its area is (b – a)². The total area of the four triangles is 4 x ½ ab = 2ab. Adding the area of the small square to it one gets the area of the large square. That is, c² = (b – a)² + 2ab = b² + a².