Elements of Descriptive Geometry: With Its Applications to Spherical Projections, Shades and Shadows, Perspective and Isometric Projections

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Barnes & Burr, 1865 - Geometry, Descriptive - 192 pages
 

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Page 67 - ... vertical trace may be constructed as in the preceding problem. Or a point of this trace may be obtained by finding the point in which the auxiliary line pierces the vertical plane. Two or more tangent planes may be passed if two or more tangents can be drawn to the base from the point in which the auxiliary line pierces the horizontal plane. Let the construction be made in accordance with the above analysis. 125. PROBLEM 20. To pass a plane tangent to a cylinder and parallel to a given right...
Page 61 - A right line is normal to a surface, at a point, when it is perpendicular to the tangent plane at that point. A plane is normal to a surface, when it is perpendicular to the tangent plane at the point of contact. Since any plane passed through a normal line...
Page 35 - F'. These points will be the foci, for DF + DF' = 2CV = VV. IV. The hyperbola, which may be generated by moving a point in the same plane, so that the difference of its distances from two fixed points shall be equal to a given line. The two fixed points are the foci.
Page 6 - If the right line be perpendicular to either plane of projection, its projection on that plane will be a point, and its projection on the other plane will be perpendicular to the ground line.
Page 55 - ... plane a meridian plane; and it is also evident that all meridian lines of the same surface are equal, and that the surface may be generated by revolving any one of these meridian lines about the axis. 97. If two surfaces of revolution having a common axis intersect, the line of intersection must be the circumference of a circle whose plane is perpendicular to the axis and center in the axis.

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