Elements of Geometry: Geometry of space

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Page 389 - The sum of the angles of a spherical triangle is greater than two and less than six right angles ; that is, greater than 180° and less than 540°. (gr). If A'B'C' is the polar triangle of ABC...
Page 472 - The area of a regular inscribed hexagon is a mean proportional between the areas of the inscribed and circumscribed equilateral triangles.
Page 386 - Two triangles are congruent if (a) two sides and the included angle of one are equal, respectively, to two sides and the included angle of the other...
Page 305 - The volume of any prism is equal to the product of its base and altitude. GIVEN— the prism ABCDE-R with base ABCDE and altitude RO.
Page 422 - The lateral area of a frustum of a cone of revolution is equal to half the sum of the circumferences of its bases multiplied by its slant height.
Page 307 - A regular pyramid is a pyramid whose base is a regular polygon, and whose vertex lies in the perpendicular erected at the centre of the base.
Page 296 - Two rectangular parallelopipeds having equal bases are to each other as their altitudes. Let AB and A'B' be the altitudes of the two rectangular parallelopipeds P and P', which have equal bases.
Page 251 - PQ, and therefore cuts MN, by the first part of the proposition. Therefore the plane CD, in which BC lies, will cut MN.
Page 374 - A spherical angle is measured by the arc of a great circle described from its vertex as a pole, and included between its sides, produced if necessary.
Page 266 - Theorem. The acute angle which a line makes with its own projection on a plane is the least angle which it makes with any line in that plane. Given the line AB, cutting plane P at 0, A'B' the projection of AB on P, and XX' any other line in P, through 0.

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