# Visualising Solid Shapes

Rectangle                                                         Square

Cuboid                                                                           Cube

Horizontal cut of the papaya

Vertical cut of the papaya

Front view of telephone

Back view of telephone

Side view of telephone

Top view of telephone

(7) A map is a pictorial presentation of a definite place.

Eg:- Map of school, map of market, map of city, map of country etc.

(8) A 3D shape with flat polygonal faces, straight edges and sharp corners (vertices), is known as polyhedra. Plural of polyhedra is known as polyhedron.

Eg:- Square, cubes, pyramid, prism etc.

(i) Prism is a polyhedron whose base and top are congruent polygons and whose lateral faces are parallelogram in shape. A prism is named after its base, as a hexagonal prism has hexagon base.

(ii) A pyramid is a polyhedron whose base is a polygon of any number of sides and whose lateral faces are triangles with a common vertex. A pyramid is named after its base, as a hexagonal pyramid has hexagon base.

(9) Types of polyhedron

(i)Convex polyhedron are those polyhedron that have no portions of their diagonals in their exteriors.

Eg:-

(ii) Concave polyhedron are those polyhedron that have some portion of their diagonal in the exteriors.

Eg:-

(iii)The polyhedron that have faces made up of regular polygons and the same number of faces meet at each vertex, are called regular polyhedron.

Eg:-

(iv) The polyhedron that have faces made up of irregular polygons and the same number of faces do not meet at each vertex, are called irregular polyhedron.

Eg:-

Euler’s Formula is a relationship among faces (F), vertices (V) and edges (E) of polyhedron.

Euler’s Formula

F + V – E = 2

Helping Topics

NCERT solutions,class 7

NCERT solutions, class 8