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THE FIRST BOOK
OF
EUCLIDE'S
ELEMENTS.
Definitions.
I. APoint is that which has no part.
II. A Line is a longitude without latitude.
III. The ends, or limits, of a line are Points.
IV. A Right Line is that which lies equally betwixt its Points.
V. A Superficies is that which has only longitude and latitude.
VI. The extremes, or limits, of a Superficies are lines.
VII. A plain Superficies is that which lies equally betwixt its lines.
VIII. A plain Angle is the inclination of two lines the one to the other, the one touching the other in the ſame plain, yet not lying in the ſame ſtrait line.
IX. And if the lines which contain the Angle be right lines, it is called a right-lined Angle.
