Young, George, jr, Baxter, Hubert Eugene, joint author · New York, The Macmillan Co. · leaf 77
al figure remain 60 DESCRIPTIVE GEOMETRY [V, § 51 on H, as above, while the figures surrounding it are rotated up-ward, swinging on the side which touches the base as an axis.Each of the vertices will move in a circular arc which is pro-jected on plan in a straight line perpendicular to its axis… … Fig. 59 (Repeated) j^ corresponding parts have equal elevations. Therefore thepoints 2*, l*, etc., are real points of intersection for these arcs.Before the rotation was started, the lines bf and bg had the pointb in common. If the points / and g have been brought togetherat 1, these lines coincide…
Geometry, Descriptive
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