Practical plane and solid geometry
Henry Angel
Paperback
(RareBooksClub.com, March 6, 2012)
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1873 Excerpt: ... of a certain quadrilateral figure. The angular points are-7", 1-2", 1", and-9 above the horizontal plane. What is its true shape t 9. A line A B, 3" long, has its extremity, A, in the vertical plane, at a height of 1-&". Its other extremity, B, is-5" above the horizontal plane. Draw its projections. 10. A line, A B, 3" long, is inclined 50 to the horizontal plane. Draw its projections when its plan makes an angle of 30 with X Y. 102 CHAPTER II. ELEMENTARY PROBLEMS ON SOLIDS. N.B.--(The problems of this chapter are to be studied simultaneously with those of Chapter I.) The following are the solids commonly used to illustrate the principles of Solid Geometry:--The cube, prism, and pyramid; the sphere, cone, and cylinder. A cube is a solid having six equal faces, all squares. A right prism is a solid having two equal and similar bases, with rectangular faces perpendicular to them. If the faces be not perpendicular to the bases, the prism is oblique. A right pyramid has one base and a number of triangular faces, meeting in a point over the centre of that base. This point is called the apex. If the apex be not over the centre of the base, the pyramid is oblique. Prisms and pyramids are named from the shapes of their bases, as square prism, hexagonal pyramid, &c. A sphere is a solid whose surface is at all parts equidistant from a point within it, called the centre. If a semicircle revolve upon its diameter, it generates the surface of a sphere. All plane sections of a sphere are circles. A cone may be defined as a pyramid with an infinite number of faces. It has a circular base, and its surface is generated by the revolution of a right-angled triangle upon its perpendicular, as an axis. A cylinder bears a similar relat...