## A Treatise on Elementary Geometry: With Appendices Containing a Collection of Exercises for Students and an Introduction to Modern Geometry |

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ABCD altitude axis base bisects called centre chord circle circumference circumscribed coincide common cone construct contain Corollary cylinder Definition denote describe diagonals diameter diedral angle difference distance divided draw drawn edges equal equivalent expressed extremities faces figure fixed follows formed four given circles given plane given point given straight line greater hence homologous indefinitely inscribed intersection joining lateral less limit locus measure meet middle point one-half opposite sides parallel parallelogram pass perimeter perpendicular plane plane MN polar pole polyedron polygon preceding prism problem proportional PROPOSITION proved pyramid quadrilateral quantities radii radius ratio rectangle respectively right angles Scholium secant segment sides similar sphere spherical square suppose surface symmetrical taken tangent tetraedron theorem third triangle ABC unit vertex vertices volume

### Popular passages

Page 19 - The perpendicular is the shortest line that can be drawn from a point to a straight line.

Page 79 - At a given point in a given straight line, to construct an angle equal to a given angle. Let A be the given point in the straight line AB, and O the given angle.

Page 216 - 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.

Page 348 - Three lines are in harmonical proportion, when the first is to the third, as the difference between the first and second, is to the difference between the second and third ; and the second is called a harmonic mean between the first and third. The expression 'harmonical proportion...

Page 254 - The angle of two arcs of great circles is equal to the angle of their planes, and 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 269 - The shortest line that can be drawn on the surface of a sphere between two points is the arc of a great circle, not greater than a semicircumference, joining the two points.

Page 263 - 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 315 - Find the locus of a point such that the sum of the squares of its distances from two fixed points shall be equivalent to the square of the distance between the fixed points.

Page 262 - Each side of a spherical triangle is less than the sum of the other two sides.

Page 175 - The projection of a point on a plane is the foot of the perpendicular from the point to the plane. The projection of a figure upon a plane is the locus of the projections of all the points of the figure upon the plane. Thus, A'B' represents the projection of AB upon plane MN.