**Exercise-10.1 **

class 8 maths chapter 10 exercise 10.1 (1)

1. For each of the given solid, the two views are given. Match for each solid the corresponding top and front views. The first one is done for you.

Solution to class 8 maths chapter 10 exercise 10.1 (1)

Solution to class 8 maths chapter 10 exercise 10.1 (1)

(a) →(iii) →(iv)

(b) → (i) → (v)

(c) → (iv) →(ii)

(d) →(v) → (iii)

(e) → (ii) → (i)

class 8 maths chapter 10 exercise 10.1 (2)

2. For each of the given solid, the three views are given. Identify for each solid the corresponding top, front and side views.

Solution to class 8 maths chapter 10 exercise 10.1 (2)

Solution to class 8 maths chapter 10 exercise 10.1 (2)

(a) →(i)→Front (ii)→Side (iii)→Top view

(b) →(i)→Side (ii)→Front (iii)→Top view

(c) →(i)→Front (ii)→Side (iii)→Top view

(d) →(i)→Front (ii)→Side (iii)→Top view

class 8 maths chapter 10 exercise 10.1 (3)

3. For each given solid, identify the top view, front view and side view.

Solution to class 8 maths chapter 10 exercise 10.1 (3)

(a) →(i)→Top view (ii)→Front view (iii)→Side view

(b) →(i)→Side view (ii)→Front view (iii)→Top view

(c) →(i)→Top view (ii)→Side view (iii)→Front view

(d) →(i)→Side view(ii)→Front view (iii)→Top view

(e) →(i)→Front view (ii)→Top view (iii)→Side view

class 8 maths chapter 10 exercise 10.1 (4)

4. Draw the front view, side view and top view of the given objects.

Solution to class 8 maths chapter 10 exercise 10.1 (4)

(a) military tent

(b) A table

(c) A nut

(d) A hexagonal block

(e) A dice

(f) A solid

**Exercise-10.2**

class 8 maths chapter 10 exercise 10.2 (1)

1 Colour the map

This is a creativity , so do your self

class 8 maths chapter 10 exercise 10.2 (2)

2 Draw a map of your class room using proper scale and symbols for different objects.

Do your self

class 8 maths chapter 10 exercise 10.2 (3)

3 Draw a map of your school compound using proper scale and symbols for various features like playground, main building, garden etc,

Do your self

class 8 maths chapter 10 exercise 10.2 (4)

4 Draw a map giving instructions to your friend so that she reaches your house without any difficulty.

Do your self

**Exercise-10.3**

class 8 maths chapter 10 exercise 10.3 (1)

1. Can a polyhedron have for its faces

(i) 3 triangles? (ii) 4 triangles?

(iii) a square and four triangles?

Solution to class 8 maths chapter 10 exercise 10.3 (1)

(i) No, a polyhedron cannot have 3 triangles for its faces.

(ii) Yes, a polyhedron can have four triangles which is known as pyramid on triangular base

(iii) Yes, a polyhedron has its faces a square and four triangles which makes a pyramid on square base.

class 8 maths chapter 10 exercise 10.3 (2)

2. Is it possible to have a polyhedron with any given number of faces? (Hint: Think of a pyramid).

Solution to class 8 maths chapter 10 exercise 10.3 (2)

It is possible, only if the number of faces are greater than or equal to 4.

class 8 maths chapter 10 exercise 10.3 (3)

3. Which are prisms among the following?

Solution to class 8 maths chapter 10 exercise 10.3 (3)

Figure (ii) unsharpened pencil

and figure (iv) a box are prisms.

class 8 maths chapter 10 exercise 10.3 (4)

4. (i) How are prisms and cylinders alike?

(ii) How are pyramids and cones alike?

Solution to class 8 maths chapter 10 exercise 10.3 (4)

(i) A prism becomes a cylinder as the number of sides of its base becomes larger and larger

(ii) A pyramid becomes a cone as the number of sides of its base becomes larger and larger.

class 8 maths chapter 10 exercise 10.3 (5)

5. Is a square prism same as a cube? Explain.

Solution to class 8 maths chapter 10 exercise 10.3 (5)

No, a square prism may be cube or cuboid.

class 8 maths chapter 10 exercise 10.3 (6)

6. Verify Euler’s formula for these solids.

Solution to class 8 maths chapter 10 exercise 10.3 (6)

(i)Here, figure (i) contains 7 faces, 10 vertices and 15 edges. Using Euler’s formula, we see F+ V=E+2 Putting F = 7, V = 10 and E = 15,

F+ V=E+2

⇒7+ 10 = 15 +2

⇒17 =17

L.H.S. = RHS.

(ii)Here, figure (ii) contains 9 faces, 9 vertices and 16 edges. Using Euler’s formula, we see F+ V=E+2 Putting F = 9, V = 9 and E = 16,

F+ V=E+2

⇒9+ 9 = 16 +2

⇒18 =18

L.H.S. = RHS.

class 8 maths chapter 10 exercise 10.3 (7)

7. Using Euler’s formula find the unknown.

Solution to class 8 maths chapter 10 exercise 10.3 (7)

In first column F=? V=6 and E=12

Using Euler’s formula, F+ V=E+2

F+ 6=12+2

⇒F+6=14

⇒F=14 –6=8

Hence there are 8 faces.

In second column F=5 V=? and E=9

Using Euler’s formula, F+ V=E+2

5+ V=9+2

⇒V+5=11

⇒V=11 –5=6

Hence there are 6 vertices.

In third column F=20 V=12 and E=?

Using Euler’s formula, F+ V=E+2

20+ 12=E+2

⇒32=E+2

⇒E=32–2=30

Hence there are 30 edges.

class 8 maths chapter 10 exercise 10.3 (8)

8. Can a polyhedron have 10 faces, 20 edges and 15 vertices?

If Faces=10, Edges=20 and Vertices=15

Then using Euler’s formula, F+ V=E+2

L.H.S=10+15=25

R.H.S=20+2=22

L.H.S≠R.H.S

a polyhedron can not have 10 faces, 20 edges and 15 vertices.

Since it doesn’t follow Euler’s formula.