Pythagorean Tangram
Pythagorean tangram can demonstrate the Pythagorean Theorem.
The third-century Chinese mathematician Liu Hui used to explain the theorem by dissecting and rearranging squares.
http://www.futilitycloset.com/2014/09/18/piece-work-2/
From Jerry Slocum, The Tangram Book, 2003.
The yellow right triangle ABC with the squares on each sides; the seven
pieces that make up squares on catheti can be rearranged to form a square on the hypotenuse.
Yellow points for translation, blue points for rotation.
Pythagorean Theorem
In Euclid's Elements is formulated by using the geometric meaning of the square. Can you write it in geometric form?