## Elements of Geometry |

### From inside the book

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**taken**chiefly from Lacroix's geometry , and forming properly a supplement to this arithmetic , is prefixed to the work , under the title of an Introduction . The parts onitted in the first edition of this translation on spherical ... Page xiv

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**taken**for unity ; then A , B , C , D , will each represent a certain number of units , entire or frac- tional , commensurable or incommensurable , and the proportion among the lines A , B , C , D , becomes a proportion in numbers ... Page 1

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**taken**, the straight line joining those points lies wholly in that surface . 7. Every surface which is neither a plane , nor composed of planes , is a curved surface . 8. A solid is that which unites the three dimensions of ex- ension ... Page 2

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**taken**together make the perimeter of the polygon . 14. The polygon of three sides is the most simple of these figures , and is called a triangle ; that of four sides is called a quadrilateral ; that of five sides , a pentagon ; that of ... Page 4

... . A straight line CD ( fig . 17 ) , which meets another straight line AB , makes with it two adjacent angles ACD , BCD , which ,

... . A straight line CD ( fig . 17 ) , which meets another straight line AB , makes with it two adjacent angles ACD , BCD , which ,

**taken**together , are equal to two right angles . Demonstration . At the point C , let CE be PART FIRST. ...### Other editions - View all

### Common terms and phrases

ABC fig adjacent angles altitude angle ACB angle BAC base ABCD bisect centre chord circ circular sector circumference circumscribed common cone consequently construction convex surface Corollary cube cylinder Demonstration diagonals diameter draw drawn equal angles equiangular equilateral equivalent faces figure formed four right angles frustum GEOM given point gles greater hence homologous sides hypothenuse inclination intersection isosceles triangle JOHN CRERAR LIBRARY join less Let ABC let fall line AC mean proportional measure the half meet multiplied number of sides oblique lines opposite parallelogram parallelopiped perimeter perpendicular plane MN polyedron prism produced proposition radii radius ratio rectangle regular polygon right angles Scholium sector segment semicircle semicircumference side BC similar solid angle sphere spherical polygons spherical triangle square described straight line tangent THEOREM three angles triangle ABC triangular prism triangular pyramids vertex vertices whence