OF GEOMETRY, CONTAINING THE FIRST SIX BOOKS OF EUCLID, WITH A SUPPLEMENT ON THE QUADRATURE OF THE CIRCLE AND THE GEOMETRY OF SOLIDS. BY JOHN PLAYFAIR, F. R. S. EDIN, PROFESSOR OY MATHEMATICS IN THE UNIVERSITY OF EDINBURGH. PHILADELPHIA, PRINTED FOR F. NICHOLS, DY THOMAS AND GEORGE PALMER, 116, HIGH'STRERT. aber ................. 1806. . A POINT is that which has position, but not magnitude.” See Notes. II.- “ the intersections of one line with another are also points. III. “ciding altogether, are called straight lines. “ther can two straight lines have a common segment ; IV. “intersections of one superficies with another are also lines.” Book I. V. VA plane superficies is that in which any two points being ta ken, the straight line between them lies wholly in that superficies. VI. lines to one another, which meet together, but are not in 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, BD, is named the angle ABD, or DBA; and that which is contained by BD, 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.' VII. other straight line makes the adja- Book I. VIII. IX. X. XI. called the circumference, and is such that all straight lines XII. XII. centre, and terminated both ways by the circumference. XIV. part of the circumference cut off by the diameter. sunnan |