1. UNIT-III PROJECTION OF SOLIDS Projection of Solids: A solid is a three dimensional object having length, breadth and thickness. It is Completely bounded by a surface or surfaces, which may be curved or plane.

2. TYPES OF SOLID Accordingly solids may be classified as polyhedra and solids of revolution. Polyhedra A polyhedra is defined as a solid bounded by plane surfaces called faces. There are two types of polyhedra which are (a) Regular, and (b)Other

3. Regular Polyhedra If the faces of a solid are equal regular polygons, it is called a regular polyhedron.

4. Prisms A prism has two bases, which are parallel to each other, and joined by three or more additional rectangular faces.

5. Other Polyhedron Prism ： A prism is a solid object with two equal parallel polygon bases and rectangular lateral surfaces. In prism, all edges are parallel to each other. edge AB ∥ edge CD ∥ edge ∥ EF

6. Pyramid A pyramid is a solid object with a polygon base and three or more additional triangular surfaces meet at a point. - Called as vertex

7. SOLIDS OF REVOLUTION Solids of revolution are obtained or generated by rotating a plane figure about one of its edges. Cylinder A cylinder is generated by rotating a rectangle plane about one of its edges. A cylinder has two equal circular bases Cone A cone is generated by rotating a right angle triangle about one of its perpendicular sides.