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Flat shapes with lines of symmetry
Textbook Part 4, pp. 34–35
GoalFind how many lines of symmetry flat shapes have.
New words
several lines · bir nechta o‘qvase · vazaregular · muntazam
Explanation
Some shapes have several lines of symmetry: a square has 4, an equilateral triangle 3, a rectangle 2, a regular pentagon 5. A circle has endlessly many — any line through its centre.
Worked examples
Square: 2 lines through the middles of the sides and 2 along the diagonals.
Rectangle (not a square): only 2 lines — folding along a diagonal does not match.
Class activity
Children cut out a square, a rectangle and a circle and fold each in different ways to find how many lines of symmetry it has.
Practice
1
How many lines of symmetry does a square have?
4
2
A rectangle (not a square)?
2
3
An equilateral triangle?
3
4
Square (4) + triangle (3) + pentagon (5) lines in total?
12