Chapter 9 – Boxes and Sketches

Page No 127:

Question 1:

Buddha wants to make a paper cube using a squared sheet. He knows that all the faces of a cube are squares. He draws two different shapes.

• Will both these shapes fold into a cube? • Draw at least one more shape which can fold into a cube. • What will be the area of each face of the cube? • Draw one shape which will not fold into a cube. • Look around and discuss which things around you look like a cube. List a few.

Answer:

• Yes, both the shapes will fold into a cube.

• The shape which can fold into a cube is shown below. 

• We know that, each face of the cube is a small square. Area of small square is 1 square cm. Thus, the area of each face of the cube is 1 square cm.

• The shape which cannot fold into a cube is shown below. 

• The shape of die, sugar cubes, ice cubes, etc. resembles that of a cube.

Page No 128:

Question 1:

All boxes are not cubes. Here are some different kinds of boxes. Match each shape below with a box into which it will fold.

Answer:

Page No 129:

Question 1:

 For making a house a floor map is first made. Have you ever seen a floor map? Here is a floor map of Vibha’s house. It shows where the windows and the doors are in the house. • Which is the front side of her house? How many windows are there on the front side? (a) 

(b) 

(c) 

(d)  Here are four deep drawings of houses. • Which one is Vibha’s house? • Why do the other three deep drawings not match the floor map? Discuss.

Answer:

• Front side of Vibha’s house is encircled in the above image.There are two windows and one door on the front side of the house.

• The front side of Vibha’s house has one door and two windows.

• The figure (c) represents Vibha’s house.

Page No 130:

Question 1:

Look at this floor map of a house. Make doors and windows on the deep drawing of this house.

• Are there any windows you couldn’t show on the deep drawing? Circle them on the floor map.

Answer:

The doors and windows on the deep drawing of the house is shown below.

There are 2 windows that could not be shown on the deep drawing. These windows are encircled on the floor map as shown below.

Question 2:

Soumitro and his friends made deep drawings of a cube. These  are their drawings. (a)  (b)  (c)  (d)  (e)  (f)  (g) 

• Which of the drawings look correct to you? Discuss. • Can you add some lines to make drawing (f) into a deep drawing of the cube?

Answer:

• The drawings (d), (e) and (g) are correct.

• The deep drawing of a cube after adding lines to figure (f) is shown below:

Page No 131:

Question 1:

This cut-out is folded to make a cube.

Which of these are the correct deep drawings of that cube? (a)

 (b)

 (c)

 (d)

(e) 

Answer:

The correct deep drawings of the given cube are :

Question 2:

Make a deep drawing of a box which looks like this.

Answer:

The deep drawing of the given box is shown below.

Page No 133:

Question 1:

• If you look at the bridge from the top, how will it look? Choose the right drawing below: a) 

b)  • Look at the photo and try to make a deep drawing of this bridge.

Answer:

The top view of the bridge is shown below.

The deep drawing of the bridge is shown below.

Question 2:

Make drawings to show how this bridge will look • From the top • From the front • From the side

Answer:

The top view of the bridge is shown below.

The front view of the bridge is shown below.

The side view of the bridge is shown below.

Question 3:

Make a matchbox model which looks like this.

 • Also make a deep drawing of the model in your notebook.

Answer:

Disclaimer: Students are advised to prepare the answer on their own.

Question 4:

How many cubes are needed to make this interesting model? • Here are some drawings of the model. Mark the correct top view drawing with ‘T’ and the correct side view drawing with ‘S’. 

(a)  (b)  (c) 

(d)

Answer:

Number of cubes in the top layer = 4 + 5 = 9 Number of cubes in the second layer from top = 4 + 5 + 3 + 4 = 16 Number of cubes in the third layer from top = 4 + 5 + 3 + 4 + 2 + 3 = 21 Number of cubes in the fourth layer from top = 4 + 5 + 3 + 4 + 2 + 3 + 2 + 1 = 24 Number of cubes in the bottom layer = 4 + 5 + 3 + 4 + 2 + 3 + 2 + 1 + 1 = 25

Total number of cubes in the model = 9 + 16 + 21 + 24 + 25 = 95

The correct drawing for the top and side view is given below:

T , S

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