1. CONGRUENCE AND SYMMETRY
GRADE 3

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Hello, How are you doing?
Today, we are going to start a new lesson on Congruence and Symmetry.

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Congruent Figures
Figures that have the same shape and same size.
Example – Figures given below are congruent.

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Line of Symmetry
A line on which a figure can be folded so that both sides match.
The given line is line of symmetry.

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Similar Figures
Similar Figures are figures that have the same shape but not the same size.
Figures given below are similar.

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Two lines of Symmetry
A figure has 2 lines of Symmetry.
Example – A Rectangle can have more than one line of Symmetry.

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Four Lines of Symmetry
Square can have four lines of Symmetry.

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No Line of Symmetry
Some Figures have no line of Symmetry. They cannot be divided into two equal parts.
The Figure has no line of symmetry.

9. Draw the line of symmetry of the figure given below.
Answer –

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Tips to Remember
Two triangles are congruent. If the position of one of the triangle is changed, they are still congruent.
Congruent Figures

11. Are the dotted lines Lines of Symmetry of the given figure.
Answer- No

12. Are the figure congruent or similar?
A B
Answer-
Similar
Neither similar nor congruent

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All the doors of the hall look like each other but are different in size. Which is true about them?
They are similar
They are congruent.
Either a or b
None of these

14. Draw the lines of symmetry of the given figures.
A B

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ASSESSMENT

16. 1. Draw the figure that is congruent to the given figure.
Answer-

17. 2. When the two figures are said to be congruent?
They have same shape
They have same length
They have same shape and size
None of these

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3. The two lenses in Era’s eyeglasses are circular in shape. They are of the same shape. Are they similar, congruent or both?
Answer - Congruent

19. 4. Write yes or no to tell if each line is a line of symmetry.
A B C
Answer –
a) No b) Yes c) No

20. 5. Which has only one line of symmetry?
A B C D
Answer - D

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6. Say True or False.
A Scalene and equilateral triangle are congruent
Pentagon can have 3 lines of symmetry.
Diagonal line of rectangle is a line of symmetry.
Answer
False

22. 7. Draw the line of symmetry for the figure given below.

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8. Two triangles are congruent. One triangle has sides of 5 cm, 9 cm and 8 cm. What are the sides of other triangle?
Answer- Same sides

24. 9. How many lines of symmetry do the following figure have?
Answer - 2

25. 10. Tell whether the figures are congruent or similar.
A B
Answer- a) Congruent
b) similar

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Recap
Congruent Figures
Line of Symmetry
Similar Figures
One line of symmetry
Two and Four Lines of Symmetry
Solved Examples
Practice Problems

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Good Work!
Now Practice worksheets on the Lesson.