The Circle, and the Measurement of Angles,..... 1 ELEMENTS OF GEOMETRY. INTRODUCTION. DEFINITIONS OF TERMS. 1. QUANTITY is any thing which can be increased, diminished, and measured. To measure a thing, is to find out how many times it contains some other thing, of the same kind, taken as a standard. The assumed standard is called the unit of measure. 2. In GEOMETRY, there are four species of quantity, viz.: LINES, SURFACES, VOLUMES, and ANGLES. These are called GEOMETRICAL MAGNITUDES. Since the unit of measure of a quantity is of the same kind as the quantity measured, there are four kinds of units of measure, viz.: Units of Length, Units of Surface, Units of Volume, and Units of Angular Measure. 3. GEOMETRY is that branch of Mathematics which treats of the properties, relations, and measurement of the Geometrical Magnitudes. 4. In Geometry, the quantities considered are generally represented by means of the straight line and curve. The operations to be performed upon the quantities, and the rela tions between them, are indicated by signs, as in Analysis. |