Chapter 15 Visualising Solid Shapes

Question 1.
If three cubes of dimensions 2 cm × 2 cm × 2 cm are placed end to end, what would be the dimension of the resulting cuboid?
Solution:
Length of the resulting cuboid = 2 cm + 2 cm + 2 cm = 6 cm
Height = 2 cm

Hence the required dimensions = 6 cm × 2 cm × 2 cm.

Question 2.
(i) Why a cone is not a pyramid?
(ii) How many dimension a solid have?
(iii) Name the solid having one curved and two flat faces but no vertex.
Solution:
(i) Cone is not a pyramid because its base is not a polygon.
(ii) Three.
(iii) Cylinder

Question 3.
Write down the number of edges on each of the following solid figures:
(i) Cube
(ii) Tetrahedron
(iii) Sphere
(iv) Triangular prism
Solution:
(i) 12
(ii) 6
(iii) 0
(iv) 9

Question 4.
What cross-section do you get when you give a horizontal cut to an ice cream cone?
Solution:
Circle.

Question 5.
Determine the number of edges, vertices and faces in the given figure.

Solution:
Edges = 8
Vertices = 5
Faces = 5

Question 6.
Draw the sketch of two figure that has no edge.
Solution:

Question 7.
Draw the sketches of two figures that have no vertex.
Solution:

Question 8.
Name any three objects which resemble a sphere and cone.
Solution:
Sphere: Football, Earth, Round table
Cone: Conical funnel, ice cream cone, conical cracker

Question 9.
What shape would we get from the given figure?

Solution:
From the given net, we get a rectangular pyramid.

Question 10.
For the solids given below sketch the front, side and top view

Solution:

Question 11.
Match the following: Solution:
(i) → (e)
(ii) → (a)
(iii) → (b)
(iv) → (c)
(v) → (d)

Question 12.
Complete the following table: Solution: Question 13.
Draw a plan, front and side elevations of the following solids.

Solution:

Question 14.
Name the solid that would be formed by each net: Solution:
(i) Triangular pyramid
(ii) Square pyramid
(iii) Hexagonal pyramid

Question 15.
Name the solids that have:
(i) 1 curved surface
(ii) 4 faces
(iii) 6 faces
(iv) 5 faces and 5 vertices
(v) 8 triangular faces
(vi) 6 triangular faces and 2 hexagonal faces.
Solution:
(i) Cylinder
(ii) Tetrahedron
(iii) Cube and cuboid
(iv) Square pyramid or rectangular pyramid
(v) Regular octahedron
(vi) Hexagonal prism.

Question 16.
Draw the top, side and front views of the given solids: Solution: Question 17.
Draw the net of a cuboid having same breadth and height, but length double the breadth.
Solution:

Question 18.
Draw the nets of the following:
(i) Triangular prisms
(ii) Tetrahedron
(iii) Cuboid.
Solution: 