# NCERT Solutions for Class 7 Maths Chapter 15

## Visualising Solid Shapes Class 7

### Exercise 15.1 : Solutions of Questions on Page Number : 281

Q1 :

Identify the nets which can be used to make cubes (cut out copies of the nets and try it): (i)The given net can be folded as follows. When the faces that are in sky blue colour and in pink colour are folded to make a cube, they will be overlapping each other.

(ii) The given net can be folded as follows. A cube can thus be formed in the above way.

(iii) The given net can be folded as follows. A cube can thus be formed in the above way.

(iv) The given net can be folded as follows. A cube can thus be formed in the above way.

(v) The given net can be folded as follows. When the faces that are in blue colour and in red colour are folded to make a cube, they will be overlapping each other.

(vi) The given net can be folded as follows. A cube can thus be formed in the above way.

Q2 :

Dice are cubes with dots on each face. Opposite faces of a die always have a total of seven dots on them. Here are two nets to make dice (cubes); the numbers inserted in each square indicate the number of dots in that box. Insert suitable numbers in the blanks, remembering that the number on the opposite faces should total to 7.

(i) The numbers can be inserted as follows so as to make the given net into a net of a dice. It can be observed that the sum of the opposite faces is 7.

(ii)The numbers can be inserted as follows so as to make the given net into a net of a dice. It can be observed that the sum of the opposite faces is 7.

Q3 :

Can this be a net for a die? Q4 :

Here is an incomplete net for making a cube. Complete it in at least two different ways. Remember that a cube has six faces. How many are there in the net here? (Give two separate diagrams. If you like, you may use a squared sheet for easy manipulation.) Q5 :

Match the nets with appropriate solids:

 (a) (i) (b) (ii) (c) (iii) (d) (iv) ### Exercise 15.2 : Solutions of Questions on Page Number : 285

Q1 :

Use isometric dot paper and make an isometric sketch for each one of the given shapes:  (i) (ii)  (iii) (iv)

Q2 :

The dimensions of a cuboid are 5 cm, 3 cm and 2 cm. Draw three different isometric sketches of this cuboid.

Q3 :

Three cubes each with 2 cm edge are placed side by side to form a cuboid. Sketch an oblique or isometric sketch of this cuboid.

Q4 :

Make an oblique sketch for each one of the given isometric shapes: Q5 :

Give (i) an oblique sketch and (ii) an isometric sketch for each of the following:

(a) A cuboid of dimensions 5 cm, 3 cm and 2 cm. (Is your sketch unique?)

(b) A cube with an edge 4 cm long.

### Exercise 15.3 : Solutions of Questions on Page Number : 288

Q1 :

What cross-sections do you get when you give a

(i) vertical cut (ii) horizontal cut

to the following solids?

(a) A brick (b) A round apple (c) A die

(d) A circular pipe (e) An ice cream cone

### Exercise 15.4 : Solutions of Questions on Page Number : 289

Q1 :

A bulb is kept burning just right above the following solids. Name the shape of the shadows obtained in each case. Attempt to give a rough sketch of the shadow. (You may try to experiment first and then answer these questions). Q2 :

Here are the shadows of some 3-D objects, when seen under the lamp of an overhead projector. Identify the solids (s) that match each shadow. (There may be multiple answers for these!) Q3 :

Examine if the following are true statements:

(i) The cube can cast a shadow in the shape of a rectangle.

(ii) The cube can cast a shadow in the shape of a hexagon.