Definition:Euclid's Definitions - Book VI

These definitions appear at the start of Book VI of by Euclid.


 * 1) Similar rectilineal figures are such as have their angles severally equal and the sides about the equal angles proportional.
 * 2) Two figures are reciprocally related when there are in each of the two figures antecedent and consequent ratios.
 * 3) A straight line is said to have been cut in extreme and mean ratio when, as the whole line is to the greater segment, so is the greater to the less.
 * 4) The height of any figure is the perpendicular drawn from the vertex to the base.