3D Shapes Class 4 Notes Maths

Understanding Shapes

Shapes are figures or objects that have a specific form or outline. They can be flat (2D) or have volume (3D). Shapes are everywhere around us and help us describe the world.

Types of Shapes

1. 2D Shapes (Two-Dimensional)

2D shapes are flat and only have length and width. They do not have any depth.

Examples of 2D Shapes:

1. Circle:

   • Round shape with no corners or edges.
   • Example: A coin.

2. Square:

   • Four equal sides and four right angles.
   • Example: A chessboard square.

3. Rectangle:

   • Opposite sides are equal, with four right angles.
   • Example: A book cover.

4. Triangle:

   • Three sides and three corners.
   • Example: A slice of pizza.

2. 3D Shapes (Three-Dimensional)

3D shapes have length, width, and depth. This means they have volume and can hold things inside them.

Examples of 3D Shapes:

1. Cube:

   • All sides are squares.
   • It has 6 faces, 12 edges, and 8 corners (vertices).
   • Think of a Rubik's cube.

2. Sphere:

   • No edges or corners.
   • It’s perfectly round in all directions.
   • Think of a soccer ball.

3. Cylinder:

   • Two identical flat circular ends and one curved side.
   • It has 2 edges and no corners.
   • Think of a soup can.

4. Cone:

   • One circular base and a single vertex (point).
   • It has 1 edge.
   • Think of a party hat.

5. Rectangular Prism (Cuboid):

   • Faces are rectangles.
   • It has 6 faces, 12 edges, and 8 vertices.
   • Think of a brick.

Solids

Solids are three-dimensional (3D) shapes that have length, width, and height. Unlike flat (2D) shapes, solids have volume, meaning they occupy space and can hold things inside them. Solids are all around us, in the form of objects we use daily.
A few objects are shown below:

Just like 2D shapes or 2-dimensional shapes have two dimensions, length and breadth.
Solid shapes, are known as 3D shapes or 3-dimensional shapes three dimensions: length, breadth and height.

Faces, Edges and Vertices of a Solid Figure

• A face is a flat surface.
• An edge is the line segment where two faces meet.
• A vertex is a point or corner where two or more edges meet.

As you can observe, the faces of a cube and cuboid are flat, whereas a cylinder, cone and sphere have curved faces.
Now, let us find out how many faces, edges and corners does each shape have. For a cube and cuboid, pick up a die and a geometry box and count the number of faces, edges and corners.
You will notice that both the cube and cuboid have 6 faces, 12 edges and 8 corners. Now, from the figure given above, try to count the same for cone, cylinder and sphere. 

You will find that:

• A cylinder has 3 faces (2 flat, 1 curved), 2 edges and 0 corners. 
• A cone has 2 faces (1 flat, 1 curved), 1 edge and 1 corner. 
• A sphere has only 1 curved surface.

Pyramid

A pyramid is a solid whose base is a polygon and the sides are triangles which meet at the top. 

This is a square pyramid, but there are also triangular pyramids, pentagonal pyramids and so on.
A square pyramid has 4 triangular faces and a square face. It has 8 edges and 5 vertices.

Net of a Cube

Take a die or any other cube and trace all its faces on a sheet of paper. What is the shape of all the six faces?
They are all squares of the same size. Thus, you see that a cube can be made from six squares joined together in a particular manner.
Let us try this combination:

A net is a two-dimensional figure that can be folded into a three-dimensional object.

We have many more nets (arrangements of these squares) that can be folded up to form a cube.
We can also form nets with 5 square faces. In this case it will be a box with no lid.

Viewing 3d Shapes

It is difficult to draw a 3D shape. So, designers use the different views of a solid to overcome this problem. A 3D shape can be viewed from the top, from the side and from the front and these views can be combined to visualise what the solid looks like.

Thus, we see that a cuboid appears to be rectangle, when viewed from any direction.
Now, let us see the different views of a car, which is a 3D shape.
Special names are given to these three views from different directions.

• When a solid is looked at from above, the view seen is called the Plan.
• The front view is called the Front Elevation.
• The side view is called the Side Elevation.

Examples:
(a) A die
(b) A solid
(c) A tent
(d)

Edurev Tips: All the views of a die (cube) are squares.