Perspective and geometrical drawing adapted to the use of candidates for second and third-class teachers' certificates . ULAR SURFACES. Square. A square is a parallelogram having two adjacent sidesequal, and the included angle a right angle. We said previously that an object appears to decrease insize as it recedes from the eye. If, therefore, a square isplaced on the ground plane with one side touching the pictureplane, it is clear that the side most removed will appearsmaller than that touching the picture plane, and so thesquare may not appear to have even one right angle. Let AB, BC,
Perspective and geometrical drawing adapted to the use of candidates for second and third-class teachers' certificates . ULAR SURFACES. Square. A square is a parallelogram having two adjacent sidesequal, and the included angle a right angle. We said previously that an object appears to decrease insize as it recedes from the eye. If, therefore, a square isplaced on the ground plane with one side touching the pictureplane, it is clear that the side most removed will appearsmaller than that touching the picture plane, and so thesquare may not appear to have even one right angle. Let AB, BC, CD, DE be all taken of equal length, and letC be on , it is plain if lines parallel to AB and of equallength be drawn on within the , they will appearshorter than AB. Find points M, N and join BM, CM, AF = AB, GB = BC = AB, etc. Hence FG = AB, GH =BC, etc., also AF = BG, BG = CH, etc., and the squares AG,BH, CK, and DL will all be equal, and the only real rightangles will be BCH and DCH; all the other angles, FAB,ABG, etc., though really right angles will not appear so.(Fig. 14.) THE squab: 29. 30 DRAWING. To represent a square perpendicular to and Let and be drawn, also , and find X, Take
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Keywords: ., bookcentury1800, booksubjectgeometricald, booksubjectperspective
