# A Text-book of Geometry (Google eBook)

Ginn & Company, 1895 - Geometry - 437 pages

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### Contents

 GEOMETRY 1 Plane Angles 7 Symmetry 13 The Circle 75 Proportional Lines and Similar Polygons 131
 Areas of Polygons 180 Eegular Polygons and Circles 211 Lines and Planes in Space 243 Polyhedrons Cylinders and Cones 278 The Sphere 339

### Popular passages

Page 98 - Any two sides of a triangle are together greater than the third side.
Page 272 - The acute angle which a straight line makes with its projection upon a plane is the least angle which it makes with any line of the plane.
Page 189 - Two triangles having 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.
Page 66 - 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 143 - Sines that the bisector of an angle of a triangle divides the opposite side into parts proportional to the adjacent sides.
Page 136 - If four quantities are in proportion, they are in proportion by composition; that is, the sum of the first two terms is to the second term as the sum of the last two terms is to the fourth term.
Page 306 - The frustum of a triangular pyramid is equivalent to the sum of three pyramids whose common altitude is the altitude of the frustum and whose bases are the lower base, the upper base, and a mean proportional between the two bases of the frustum.
Page 354 - A spherical polygon is a portion of the surface of a sphere bounded by three or more arcs of great circles. The bounding arcs are the sides of the polygon ; the...
Page 405 - Show that the locus of a point which moves so that the sum of its distances from two h'xed straight lines is constant is a straight line.
Page 134 - If the product of two quantities is equal to the product of two others, either two may be made the extremes of a proportion and the other two the means.