Math Trivia : Cut a square and create two squares

△ ABC is a right-angled triangle whose ∠ A = 90 degree. The area of square Y + Z = X (Pythagorean theorem) 
Then, when you cut off square X and make Y, Z of pieces of X, show the lines you cut.   





As shown in the figure below, figures with same number are congruent. 

Thus cut off square X as below.