Appleton's cyclopædia of drawing, designed as a textbook for the mechanic, architect, engineer, and surveyor (1866)
Worthen, William Ezra, 1819-1897, [from old catalog] ed, Appleton, firm, publishers, New York. (1866. D. Appleton & co.) [from old catalog] · New York, D. Appleton and company · leaf 23
ontained by the straight lines, AB, CB, is named the angle ABC, or CBA ; bnt 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. When a straight line standing on another straight line makes the adja-cent angles equal to one another, each… … Fig. 6. An acute angle is that which is less than a right angle (fig. 5). A triangle is a flat surface bounded by three straight lines; when thethree sides are equal, the triangle is equilateral; when only two of itssides are equal, isosceles ^ when none equal, scaline; when one of theangles is a…
