Technical Terms used in Solids

TECHNICAL TERMS USED IN SOLIDS

1. Face: The regular plane surface which form the surface of a solid. 

2. Edge: The line along which two plane faces (or) surfaces meet.

3. Top base: Upper plane surface of a solid.

4. Bottom base: Lower plane surface of a solid. 

5. Axis of prism: An imaginary line joining the centres of top base and bottom base. 

6. Axis of pyramid : An imaginary line joining the apex and centre of bottom base.

7. Regular solid: A solid in which axis is perpendicular to its base.

8. Oblique solid: A solid in which axis is inclined to its base. (Fig. 14.5)

9. Apex of a pyramid : The point at which all equal isosceles triangular faces meet.

10. Slant Edge: The line joining the apex and the corner of the base.

11. Generator: Straight line drawn from the apex to the circumference of the base circle of a cone. The length of generator is the slant height of the cone.

12. Frustum : When a solid is cut by a section plane parallel to its base and on removing the upper portion of the solid, the remaining portion is called the frustum of solid. (Fig. 14.6).

13. Truncated solid: When a solid is cut by a section plane inclined to its base, and on removing the upper portion of the solid, the remaining portion is called the truncated solid. (Fig. 14.7).

Note: 1. Only the projections of Right Regular solids (ie., solid with axis perpendicular to the base and all bounding faces are similar shape and size) are presented in this chapter. Hence a solid in any problem is to be understood as right regular solid.

2. Also, only the projections of full solids (Not Frustum (or) truncated) are dealt in this chapter.