CBSE Class 4 Maths Revision Worksheet Set 19

Question 1. Who am I?
(1) I have one face, no vertex and no edge.
Answer: I am a sphere.
In simple words: A sphere is round like a ball, having only one curved surface with no corners or edges.

Exam Tip: Remember that a sphere has 0 vertices and 0 edges, unlike flat-faced 3D shapes.

(2) I have 2 faces, 1 edge and 1 vertex.
Answer: I am a cone.
In simple words: A cone has a flat circular base (1 face), a curved surface leading to the top point (making 2 faces in total), 1 circular edge, and 1 top corner vertex.

Exam Tip: Visualize an ice cream cone to easily count its faces, edge, and vertex.

(3) I am the longest chord of a circle.
Answer: I am a diameter.
In simple words: The diameter is a straight line passing through the center of a circle, connecting two points on its boundary, and it is always the longest possible chord.

Exam Tip: Always remember that the diameter is twice the length of the radius (\(d = 2r\)).

Question 2. Write the shape of the following object:
a. Book
Answer: Cuboid
In simple words: A book has six rectangular faces, making its 3D geometric shape a cuboid.

Exam Tip: Objects with rectangular faces of varying lengths are always cuboids.

b. Tube light
Answer: Cylinder
In simple words: A tube light has a long straight tubular body with two circular ends, which is the shape of a cylinder.

Exam Tip: Think of pipes, pencils, and tube lights as everyday examples of cylinders.

c. Marble
Answer: Sphere
In simple words: A marble is perfectly round like a ball, so its shape is a sphere.

d. Tennis ball
Answer: Sphere
In simple words: Just like a marble, a tennis ball is a round 3D object shaped like a sphere.

Exam Tip: Balls used in sports are standard examples of spherical shapes.

e. Sugar cube
Answer: Cube
In simple words: A sugar cube has six equal square faces, so its shape is a cube.

Exam Tip: If all length, width, and height dimensions are equal, the 3D shape is a cube.

f. Shoe box
Answer: Cuboid
In simple words: A shoe box has rectangular faces where opposite sides are equal, forming a cuboid.

Exam Tip: Boxes designed to hold shoes or gifts are typically cuboid in shape.

Question 3. How many line segments can you draw from the points given below? Draw and name them.
Answer: Total number of line segments = 6.
The given points are A, B, C, and D. By connecting every pair of points, we get the following line segments:
1. Line segment AB
2. Line segment AC
3. Line segment AD
4. Line segment BC
5. Line segment BD
6. Line segment CD
In simple words: We find the total number of line segments by connecting each point to every other point using combinations. For 4 points, we can form 6 unique line segments.

Exam Tip: Use the combination formula \(\frac{n(n-1)}{2}\) where \(n\) is the number of points. For \(n = 4\), \(\frac{4 \times 3}{2} = 6\) line segments.