Perspective and geometrical drawing adapted to the use of candidates for second and third-class teachers' certificates . In first, let AB be the given line; erect at A a perpendicularand make it equal to AB; with centre C and distance CAdescribe arc AD; with centre B and distance BA describe GEOMETRICAL DRAWING. 107 arc to meet former arc in D; join CD and BD, completingthe square. (Fig. Q6,) . (b) On a given diagonal AB. With centre A and distance greater than half of AB, de-scribe arc CD, and with centre B and same distance describean arc to cut former arc in C and D; join CD and produceboth
Perspective and geometrical drawing adapted to the use of candidates for second and third-class teachers' certificates . In first, let AB be the given line; erect at A a perpendicularand make it equal to AB; with centre C and distance CAdescribe arc AD; with centre B and distance BA describe GEOMETRICAL DRAWING. 107 arc to meet former arc in D; join CD and BD, completingthe square. (Fig. Q6,) . (b) On a given diagonal AB. With centre A and distance greater than half of AB, de-scribe arc CD, and with centre B and same distance describean arc to cut former arc in C and D; join CD and produceboth wajs; with centre E and distance E A or EB describe acircle cutting diameter in F and G; join FA, FB, GA andGB, completing the square. (Fig. 67.) iTo. 3,—To construct an oblong of given Fig. 68. Let AB represent the greater side; erect AG perpendicularto AB at A, and with centre C and distance equal to ABdescribe an arc; with centre B and distance equal to ACdescribe an arc cutting former arc in D; join DC and DB,Gompleting the required oblong. (Fig. 68.) iVo. ^.—To divide a given line into (a) two equal parts. Fig-. GO. 108 DRAWING. Let AB be the given line; with centre A and distance equalto more than half of AB describe an arc, and with centre Band same distance describe an arc cutting former in C and D;join CD, cutting AB in E into two equal parts. (Fig. 69.) (b) Into any number of equal parts. Note.—Before this can be done it is necessary to show howto draw a line parallel to another from an external point. Cy -^ D
Size: 2046px × 1221px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, booksubjectgeometricald, booksubjectperspective
