This is the tangram from Section 10.3 but the vertices of the pieces have been labelled. The top left-hand corner of the square is labelled A, the top right-hand corner is labelled B; the bottom right-hand corner is labelled C and the bottom left-hand corner is labelled D. The midpoint of BC is labelled J and the midpoint of DC is labelled H. The midpoint of HJ is labelled I. The midpoint of BD is labelled F and the midpoint of BF is G and the midpoint of FD is E.