Page:Euclid's Elements 1714 Barrow translation.djvu/15

Rh dividing the circle into two equal parts.

XVIII. A Semicircle is a figure which is contained under the diameter, and under that part of the circumference which is cut off by the diameter.

In the circle EABCD, E is the center, AC the diameter, ABC the emicircle.

XIX. Right-lined figures are uch as are contained under right lines.

XX. Three-ided or Trilateral figures are uch as are contained under three right lines.

XXI. Four-ided or Quadrilateral figures are uch as are contained under four right lines.

XXII. Many-ided figures are uch as are contained under more right lines than four.



XXIII. Of Trilateral figures, that is an Equilateral Triangle, which hath three equal ides; as the Triangle A.



XXIV. Ioceles is a Triangle which hath only two ides equal; as the Triangle B.



XXV. Scalenum is a Triangle whoe three sides are all unequal; as C.