Descriptive Geometry

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McGraw-Hill book Company, Incorporated, 1918 - Geometry, Descriptive - 112 pages
 

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Page 68 - Therefore, to make the construction for the tangent plane, pass a plane through the center of the sphere and perpendicular to the line MN.
Page 24 - The angle between a line and a plane is the angle between the line and its projection on the plane; therefore, project the given line on the given plane, pass a plane m FIG.
Page 83 - SECTIONS OF A CONE The circle, parabola, ellipse, and hyperbola are known as conic sections because each may be obtained by cutting a cone by a plane. If the cutting plane is perpendicular to the axis of the cone, the section is a circle.
Page 66 - Fig. 55, and let P be the given point. Analysis. Since the required plane must contain a rectilinear element, it will pass through the vertex; hence, if we join the given point with the vertex by a right line, it will be a line of the required plane, and pierce the horizontal...
Page 95 - This surface may be generated (1) by the rotation of a straight line about an axis not in the same plane...
Page 38 - If a line lies in a plane, the traces of the line lie in the traces of the plane; and conversely.
Page 87 - ... in the simplest manner, that is, in straight lines or circles, we have the following principles. To cut right lines, at once, from two cylinders, as in Fig. 5, a plane must be parallel to both their axes. To cut a cylinder and cone, at once, in the same manner, as in Fig. 7, each plane must contain the vertex of the cone, and be parallel to the axis of the cylinder. To cut elements at once from two cones, a plane must simply contain both vertices.
Page 54 - Hence, if a right line is perpendicular to a plane, its projections are perpendicular to the traces of the plane, respectively.
Page 55 - Through a given point to draw a line perpendicular to a given plane: (1) the point being without the plane, (2) the point being in the plane.

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