294 



DEFINITIONS OF MATHEMATICAL FORMS. 



FIG. 12. 



Fia. 13. 



FIG. 14. 



FIG. 15. 



FIG. 11. ^ Solid has three dimensions length, 



breadth, and thickness ; as, Fig. 11. 



A Prism is a solid whose sides are paral- 

 lelograms, and whose ends are equal and 

 similar ; as, Fig. 12. 



When the ends of a prism are triangular, 

 it is called a triangular prism / as, Fig. 12. 

 When the ends of a prism are square, it 

 is called a square prism ; as, Fig. 13. 



When the ends of a prism are hexagonal,, 

 it is called a hexagonal prism ; as, Fig. 14. 



When the ends of a prism are circular, it 

 is called a cylinder ;* as, Fig. 15. 



When all the sides of a rectangular prism 

 are square, it is called a cube ; as, Fig. 16. 

 A Pyramid is a solid, the base of which is a 

 plane rectilinear figure, and having sides which 

 are triangles whose vertices meet at a point at 

 the top called the vertex of the pyramid. Fig. IT. 

 The Altitude of a pyramid or a cone is the 

 perpendicular distance from the vertex to the 

 plane of the base ; as, Fig. IT. 



A Cone is a solid, the base of which is ?, circle, 

 and which tapers uniformly to a point at the top 

 called a vertex. Fig. 18. 



A cylinder is a regular polygon, or prism, with an infinite number of sides. 



FIG. 1(5. 



FIG. 17. 



FIG. IS. 



