Descriptive geometry for students in engineering science and architecture; a carefully graded course of instruction . Fig. 91. The point A is common to both planes, the 40° and the 70°; so, also, is thepoint // where the two planes meet. Join // to a therefore, and so obtainthe plan of the intersection of the 40° plane with the 70° plane. This line will con-tain the edge of the cube common to the two faces whose inclinations are to ha2, and using ao as the comer for a square, mark off J2C2 on therabatted line, and also make d-ido perpendicular to it. These measurements,
Descriptive geometry for students in engineering science and architecture; a carefully graded course of instruction . Fig. 91. The point A is common to both planes, the 40° and the 70°; so, also, is thepoint // where the two planes meet. Join // to a therefore, and so obtainthe plan of the intersection of the 40° plane with the 70° plane. This line will con-tain the edge of the cube common to the two faces whose inclinations are to ha2, and using ao as the comer for a square, mark off J2C2 on therabatted line, and also make d-ido perpendicular to it. These measurements, in 90 DESCRIPTIVE GEOMETRY the case of a cube, will be the same as that of ab previously chosen as the lengthof an edge of the cube, or they should be made the same as the edges of the40° face of the prism, if it be a prism that has to be Fig. 02. It will readily be seen that from this rabattement of the two edges the plansac and ad may be obtained. Three edges are now found in plan, namely AB^ PROJECTION OF SOLIDS DEPEXDEXT OX TAXGEXT PLAXES 91 AC and AD, and parallels to these will be necessary in order to complete theplan of the cube. Of the two faces found in the figure, the face dace is a 40° face, and the facebacf is a 70° face. In Fig, 92 is shown the case of a pyramid in which the mjth ;d requiresthe employment of two right circular cones, since the triangular faces of the solidare inclined to the plane of the base. Let it be required to find the plan of a square pyramid when the base is inclinedat, say, 45° to the and one triangular face is at, say, 65° to the The baseplane is marked RST in the figure, and is purposely arranged perpendicularlyto the in order to simplify the work. At (i) in the figure the square pyramidis set up in plan and elevation in such a way as to find the angle, a^, of
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Keywords: ., bookcentury1900, bookdecade1910, bookpublisheretcetc, bookyear191
