Functional Skills: Symmetry and 2D Shapes
Functional Skills: Symmetry and 2D Shapes Revision
Symmetry and 2D Shapes
We’ll now look at some 2D Shapes, and in particular, we’ll look to compare their lines of symmetry.
Lines of Symmetry
A line of symmetry for a shape is easy to find. Imagine your shape is made of paper. Now, fold it in half. If there’s any way you can fold the shape in half to have a perfect overlap (i.e. no extra pieces on either side), you have found a line of symmetry along the fold.
Look at the image on the right. The shape folds in half along the dotted line. The dotted line is the line of symmetry.
Some shapes have two or more lines of symmetry.
Take a look at the shape on the right.
It can be folded in half 2 ways, so it has 2 lines of symmetry.
Some shapes have no lines of symmetry.
Take a look at the shape on the right.
This shape cannot be folded in half in any direction, so it has no lines of symmetry.
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2D Shapes
2D shapes are flat shapes. We have an infinite number of them, and have specific names assigned to each of them.
So, in order of number of sides:
- Circle
- Semicircle
- Triangle
- Quadrilateral (these can be squares or rectangles, or other shapes with 4 sides)
We do have more names beyond here, but we’ll rarely deal with these shapes.
Circles:
- One curved side
- No corners
Triangles:
- Three straight sides
- Sides can be different length
- Three corners
- Angles at corners can be different sizes
This triangle has:
- 2 sides of the same length, and one of different length
- 2 angles that are the same (the bottom ones)
- 1 line of symmetry
Other triangles may have different properties.
Squares:
- 4 straight sides
- All sides are the same length
- 4 corners
- All angles at corners are right angles
- 2 lines of symmetry
Rectangles:
- 4 straight sides
- Sides opposite to each other are the same length
- 4 corners
- All angles at corners are right angles
- 2 lines of symmetry
Functional Skills: Symmetry and 2D Shapes Example Questions
Question 1: What are the names of these shapes?
a)
b)
c)
[3 marks]
a) Square
b) Triangle
c) Circle
Question 2: Indicate the lines of symmetry on each shape, and write the number of lines of symmetry for each.
[4 marks]
Question 3: Mark all lines of symmetry for the shape below. State the number of lines of symmetry.
[2 marks]
There are 5 lines of symmetry.