Descriptive geometry for students in engineering science and architecture; a carefully graded course of instruction (1915)
Armstrong, Henry F. (Henry Fry), 1868- · New York, J. Wiley & sons, inc.; [etc., etc.] · leaf 42
Fig. 3j. In Fig. 33 a regular pentagonal pyramid is made to rest with one of its tri-angular faces in the H.P. and the axis of the solid—the line from its apex to thecentre of its base—is at 30° to the V.P. This means that the compound angle … Fig. must be found for the axis, since there are two angles to be taken into consideration,namely, the angle a° which it makes with the H.P.. and the 30^ angle it makes withthe \.P. In the fmal position, therefore, the plan oi the axis is made parallel tothe arrow line obtained by compounding these…
Geometry, Descriptive
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