Perspective and geometrical drawing adapted to the use of candidates for second and third-class teachers' certificates . Fig. 102. Let AC and BC be the given lines; place them in astraight line AB; bisect AB in D, and on AB describe 130 DRAWING. semicircle AEB; through C draw CE at right angles to ABthen will AC: CE:: CE: CB. (Fig. 102.) (b) To draw a third proportional to two given lines. Let AB and BC be the given lines; draw AE, making anyangle with AC; make AD = BC; join BD, and through Cdraw CE parallel to BD, meeting AD produced : then willAB:BC::BC:DE. (Fig. 103.) If BC be greater than
Perspective and geometrical drawing adapted to the use of candidates for second and third-class teachers' certificates . Fig. 102. Let AC and BC be the given lines; place them in astraight line AB; bisect AB in D, and on AB describe 130 DRAWING. semicircle AEB; through C draw CE at right angles to ABthen will AC: CE:: CE: CB. (Fig. 102.) (b) To draw a third proportional to two given lines. Let AB and BC be the given lines; draw AE, making anyangle with AC; make AD = BC; join BD, and through Cdraw CE parallel to BD, meeting AD produced : then willAB:BC::BC:DE. (Fig. 103.) If BC be greater than AB, DE will be a third proportionalgreater; but if BC be less than AB, DE will be less IS
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Keywords: ., bookcentury1800, booksubjectgeometricald, booksubjectperspective
