A 2D shape is symmetrical if you can draw a line through it and it looks exactly the same either side.
This line is called a line of symmetry.
Oh that rather smug expression tells me that square knows a thing or two about symmetry.
So, let’s have a look then. One vertically down the middle, two, horizontally across the middle. Three, diagonally left to right. And diagonally right to left.
Oh, very ‘arty’.
An isosceles triangle has just one. Rectangles have two, and circles…
Well they are an interesting one. Circles have endless lines of symmetry, as long as you go through the centre point, it’s always symmetrical.
Let’s just do a few around him.
Symmetry is said to be one of the things humans find very attractive but eh, what do you think guys?
SHAPES: Cheer!
Symmetry
A 2D shape is symmetrical if a line can be drawn through it so that either side of the line looks exactly the same.
The line is called a line of symmetry.
This is sometimes called a 'mirror line' or 'mirror symmetry', because if you put a mirror on the line, the reflection would show the whole shape.
• An isosceles triangle has 1 line of symmetry.
• A square has 4 lines of symmetry.
• A circle has unlimited lines of symmetry!
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