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lem is inclined at 60 and 30 to the HP, with one of its sides touching the VP and an adjacent side the HP ; to find its plan and elevation in those positions. At B in the IL, draw BC, BC' (both equal to AB) with the 60 set- square, making angles of 60 and 30 with the IL ; then BC, BC' are the required elevations of the square at those angles. From BcZd', draw BA, dc, d'c, perpendicular to the IL, and each equal to BC ; and Ace parallel to it ; then B Acd ; EAc'd' are the plans of the given square when inclined at 60 and 30 to the HP. The projections of the rect- angle are not given, as the method of obtaining them is in all respects the same as that for the square, but allowing for the difference of length of adjacent sides. 20. The method of obtaining the projections of a pentagon and hexagon in different positions with respect to the VP and HP is fully shown in Figs. 81 88, and will not need explanation further than to say that the elevations in Figs. 81 and 85 shown with reference letters in capitals must be drawn first, according to the construction rules given in Problems 19 and 20, before their plans can be found ; in all other respects the procedure is the same as in the previous figures. To make himself thoroughly conversant with the application of the principles of projection to the delineation of plane figures, which it is most important he should be before passing on to the projection of solids, the student should draw all the foregoing plane figures at least twice, making them three times the size here given. 48 MECHANICAL AND ENGINEERING DRAWING -TJ