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1. Point is that which hath no parts, or which hath no magnitude. Set Motes.
II. A line is length without breadth.
Set N. plane, which meet together, but are not in the same direction.”
IX. A plane rectilineal angle is the inclination of two straight lines to one another, which meet together, but are not in the fime straight line.
'N. B. When several angles are at one point B, any one of them is expressed by three letters, of which the letter that is at the vertex
of the angle, that is at the point in which the straight lines that ' contain the angle meet one another, is put between the other two
letters, and one of these two is somewhere upon one of those straight lines, and the other upon the other line. thus the angle which is ' contained by the straight lines AB, CB is named the angle ABC, or CBA; that which is contained by AB, DB is named the angle
; ' ABD, or DBA; and that which is contained by DB, CB is called ' the angle DBC, or CBD, but if there be only one angle at a point, ‘ it may be expressed by a letter placed at that point; as the angle at E.'
straight line makes the adjacent angles
An obtuse angle is that which is greater than a right angle.
circumference, and is such that all straight lines drawn from a cer-
A A A
and all its angles right angles.
not right angles,
ther, but all its sides are not equal, nor its angles right angles,
Book 1. All other four sided figures besides these, are called Trapeziums.
being produced ever so far both ways, do not meet.
POSTULAT E S.
from that center,
A X I 0 M S.