Recognition of Solids ICSE Class-7th Concise Selina mathematics Solutions Chapter-18 (Representing 3-D in 2-D). We provide step by step Solutions of Exercise / lesson-18 Recognition of Solids for ICSE Class-7 Concise Selina Mathematics. Our Solutions contain all type Questions of Exe-18 to develop skill and confidence. Visit official Website CISCE for detail information about ICSE Board Class-7.
Recognition of Solids ICSE Class-7th Concise Maths Selina Solutions Chapter-18 (Representing 3-D in 2-D)
Exercise – 18
Question 1.
Identify the nets which can be used to form cubes
Options
(a) Yes
(b) No
Answer
(i) (b) No
The net can not be used to form a cube.
(ii) (a) Yes
The net can be used to form a cube.
(iii) (a) Yes
The net can be used to form a cube.
(iv) (a) Yes
The net can be used to form a cube.
(v) (b) No
The net can not be used to form a cube.
Question 2.
Draw at least three different nets for making cube.
Answer
Question 3.
The figure, given below, shows shadows of some 3D objects, when seen under the lamp of an overhead projector :
In each case, name the object.
Answer
(i)
(ii)
(iii)
Question 4.
Using Euler’s formula, find the values of a, b, c and d.
| Faces | a | 5 | 20 | 6 |
| Vertices | 6 | b | 12 | d |
| Edges | 12 | 9 | c | 12 |
Answer
| Faces | a | 5 | 20 | 6 |
| Vertices | 6 | b | 12 | d |
| Edges | 12 | 9 | c | 12 |
(i)
a + 6 – 12 = 2
a = 2 – 6 + 12
= 14 – 6
= 8
(ii)
b + 5 – 9 = 2
6 = 2 + 9 – 5
= 6
(iii)
20 + 12 – c = 2
32 – c = 2
⇒ c = 32 – 2
⇒ c = 30
(iv)
6 + d – 12 = 2
d – 6 = 2
d = 2 + 6
= 8
Question 5.
Dice are cubes with dot or dots on each face. Opposite faces of a die always have a total of seven on them.
Below are given two nets to make dice (cube), the numbers inserted in each square indicate the number of dots in it.
Insert suitable numbers in each blank so that numbers in opposite faces of the die have a total of seven dots.
Answer
(i)
(ii)
Question 6.
The following figures represent nets of some solids. Name the solids
Answer
(i) The given nets of the solid is a cube.
(ii) The given nets of the solid is a cuboid
Question 7.
Draw a map of your class room using proper scale and symbols for different objects.
Answer
Question 8.
Draw a map of your school compound using proper scale and symbols for various features like play ground, main building, garden, etc.
Answer
Question 9.
In the map of India, the distance between two cities is 13.8 cm.
Taking scale : 1 cm = 12 km, find the actual distance between these two cities.
Answer
The scale for a map is given to be 1 cm = 12 km
The distance between these two cities
= 13.8 cm on the map
so Actual distance between these two cities
= 12 × 13.8 km
= 165.6 km
— End of Recognition of Solids ICSE Class-7th Solutions :–
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