Then BH is equal to BK, DL, EH.
Now BH is the rectangle A, BC,
for it is contained by GB, BC, and BG is equal to A;
BK is the rectangle A, BD,
for it is contained by GB, BD, and BG is equal to A;
and DL is the rectangle A, DE,
for DK, that is BG [I. 34], is equal to A.
Similarly also EH is the rectangle A, EC.
Therefore the rectangle A, BC is equal to the rectangle A, BD, the rectangle A, DE and the rectangle A, EC.