Shapes

 Mind Maps

Class III - maths: Shapes
Q) Which of these has the maximum number of vertices? (a) square (b) triangle (c) circle?

Q) Write the shape of this object A set of square in the geometry box ?

Q) What is line segment?

Q) What is curved lines?

Q) What is point?

Q) What is closed figure?

Q) What is open figure?

Q) What is face?

Q) What is edge?

Q) What is vertex?

Q) What is solid?

Q) What is measuring line segments?

Q) Draw two closed figures using curved lines and explain about intersecting lines ?

Q) Draw 2 horizontal straight line, 2 vertical straight lines, and 2 oblique straight lines. Name them?

Q) How many Faces,curved/flat,edges,vertices of cube and cuboid?

Q) How many Faces,curved/flat,edges,vertices of sphere and cone?

Q) How many Faces,curved/flat,edges,vertices of cylinder and sphere?

Q) How many corners and sides are there in rectangle,sphere,triangle?

Q) How many corners and sides are there in Circle,oval,curved lines?

Q) Name the lines shown on the rigth. Name the points of intersection?

Q) Explain about plain and curved surface?

Q) Explain about Tangram and congruent figures?

### Understanding Simple Concepts In Geometry

#### 1. Point

• This is point. We name it by any capital letter of the alphabet, e.g., P.
• A point can be made by the tip of your pencil.
• A point is so small that it has to be drawn very carefully. It shows a definite position
• #### 2. Straight line

• This is a geometrical straight line. It has an arrowhead on both sides to show that we can make it longer on either side
• We mark points on both sides of the line and name the points A, B, etc. now, we can name the straight line AB.
• A line has no end points, it has no definite length.
Straight lines can be made in any direction.
horizontal straight line.
vertical straight line.
slanting straight line.
We can call it oblique line.

#### 3. Line segment

The straight line between two points is called a line segment.

Here, AB/DC is a line segment.
• The points A and B are called the end points of the line segment AB.
• A line segment can be measured with a scale, it has a definite length.
• It has no breadth or thickness.
• #### 4. Ray

• AB is a ray. It has one arrowhead to show that it can be made longer from the side of B.
• A ray AB has one end point A. The point A is called the initial point of ray AB.

#### 5. Intersecting lines

Lines GH and KL are crossing each other at a point P.
So, these are intersecting lines. P is called the point of intersection.

#### 6. Curved lines

Curved lines are fun lines and can be made anyway you like.

### Word Problems

#### Measuring Line Segments

• We measure the length of a line segment with the help of a ruler or a 15 cm scale
• To measure the length of a line segment AB, put the scale along the line segment in such a way that one of its edges touches both the points A and B and the 0 mark of the scale is at A. Now, read the scale at mark B.
• The reading of the scale at mark N gives the length of the line segment MN in centimeters.

#### Drawing A Line Segment Of A Given Length

To draw a line segment of a given length, say 5 cm, we proceed as per the following steps.

• Step 1: Take a pencil and a scale.
• Step 2: put the scale on a sheet of paper and hold it firmly.
• Step 3: With the help of a sharp pencil, mark a point X against the 5 cm mark of the scale.
• Step 4: Join the points X and Y. Thus, we obtain the line segment XY of length 5cm.

### Solids

An object that occupies space is called a solid. Solids are 3 dimensional and not like plane figures. These are some of the solids you already know.

#### Plane And Curved Surfaces

• We have learnt that a solid occupies space. The part of a sold which we usually see and touch is called its surface.
• Look at the surfaces of these objects.
• We see that one pair of objects has a different surface than the other.
• The scale and the book have plane surfaces
• The cricket ball and the balloon have curved surfaces.
• Some objects like a coke can have both plane and curved surface.

#### FACES, EDGES AND VERTICES

• A face is the surface of a solid
• Two faces meet at an edge
• Two edges meet at a point known as vertex. (plural of vertex is the vertices.)

#### DESCRIPTION OF SOLIDS

• A cube is made up of 6 square faces, 12 straight edges, and 8 vertices
• A cuboid is made up of 6 rectangular faces,12 straight edges, and 8 vertices
• A sphere has 1 curved face. It has no edge and no vertex
• A cone has 1 flat and 1 curved face. It has 1 curved edge and 1 vertex
• A cylinder has 2 flat faces and 1 curved face. It has 2 curved edges and has no vertex.

### Closed And Open Figures

##### Closed figures

Figures that start and end at the same point are called closed figures.

##### Open figures

Figures that start at one point and end at another point are called open figures.

##### TANGRAM
• Tangram is old Chinese puzzle consisting of flat pieces of shapes called 'tans'
• Tangram has either 5 or 7 pieces
• Pieces of a tangram can be put together to form different shapes. A 7 piece tangram looks as shown alongside. The pieces can be cut out and interesting shapes like animals, people, and things can be made
• RunningMan  Swan   Fish
##### CONGRUENT FIGURES

Figures that have the same shape and are of the same size are called congruent figures.

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