Page 225 - ICSE Math 7

THINK SMART

1. What is the relation between the faces, edges and vertices of a polyhedron? An icosahedron has
12 vertices, 20 faces and n edges. Find n.

2. Construct a 3D shape whose different views are as given below:

Front Side Top

Group Activity

Objective: To form a three-layered structure using cubes as shown in the given figure

Material required: Cubes of identical size, pen, paper
Answer the following questions.

(a) How many cubes are there in the 3 layers?
(b) How many cubes are used for the middle layer?

(c) How many cubes are required for the base layer? If this
pattern is continued, how many cubes would be in the
base layer of a structure having 4 layers, 5 layers, n layers?

Note: Make identical cubes of cardboard if readymade cubes are not available.

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