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ABCDE altitude auxiliary circle bisects called centre chord circumference circumscribed coincide convex cube curve diameter dihedral angles directrix distance draw drawn ellipse equidistant equivalent face angles feet Find the volume focal radii foci frustum given plane given point Hence homologous hyperbola inches inscribed intersection lateral area lateral edges lateral faces latus rectum limit lune parabola parallel planes parallelogram pass a plane perimeter perpendicular plane MN plane parallel plane passing PMē polyhedral angle polyhedron prismatoid Proof prove Q. E. D. PROPOSITION radius rectangular parallelopiped regular polygon regular pyramid respectively right circular cone right circular cylinder right prism right section S-ABC segment similar slant height sphere spherical angle spherical polygon spherical triangle square straight line symmetrical tangent tetrahedron THEOREM total surface triangular prism trihedral upper base vertex vertices Wentworth's
Page 274 - If two planes are perpendicular to each other, a straight line drawn in one of them, perpendicular to their intersection, is perpendicular to the other.
Page 383 - Hence the two last are right angles ; hence the arc drawn from the vertex of an isosceles spherical triangle to the middle of the base, is at right angles to the base, and bisects the vertical angle.
Page 250 - The areas of two triangles which have an angle of the one equal to an angle of the other are to each other as the products of the sides including the equal angles. To prove that Proof. A Let the triangles ABC and ADE have the common angle A. A ABC -AB X AC Now and A ADE AD X AE Draw BE.
Page 285 - The sum of the face angles of any convex polyhedral angle is less than four right angles.
Page 246 - PERIPHERY of a circle is its entire bounding line ; or it is a curved line, all points of which are equally distant from a point within called the centre.
Page 245 - The straight line joining the middle points of two sides of a triangle is parallel to the third side and equal to half of it 46 INTERCEPTS BY PARALLEL LINES.
Page 254 - If a straight line is perpendicular to each of two other straight lines at their point of intersection, it is perpendicular to the plane of the two lines.
Page 295 - An oblique prism is equivalent to a right prism whose base is equal to a right section of the oblique prism, and whose altitude is equal to a lateral edge of the oblique prism. r Let FI be a right section of the oblique prism AD', and PI" a right prism whose lateral edges are equal to the lateral edges of AD'.