Rotational Symmetry?

Question

ok im really hoping u can tell what the shapes below are and if u can tell what they are then can you please tel me which one of them has rotational symmetry
__
|...|
|...L___
|_____ | A

....... ______
........|......___|
........|......|
___|......|
.|______| B

.....___
__|......|__
|_______| C


(ignore the full stops)

thanks in advance

Answer 1

It sounds to me as if the main problem is that you don't know what "rotational symmetry" means! Normally when you think of something being "symmetrical" you probably think of things where one side is like the other, so that if, say, you folded a symmetrical thing in half, then one half would sit on top of the other. A person is (approximately) symmetrical down the middle of the body (at least on the outside), but NOT symmetrical from top to bottom. If you crease yourself in half (like when you touch your toes), the two halves don't match (you've got feet in one place but a head at the other) ... so you are symmetical about your vertical midline, but not about your horizontal midline. Now to rotational symmetry. Things that are rotationally symmetric can be turned around (rotated) about a point in the middle so that the new position fits exactly over the old position. A square is rotationally symmetric because a 90 degree turn will leave the shape looking exactly as it was. A rectangle is also rotationally symmetric because a 180 degree turn will leave a rectangle looking the same (although a 90 degree turn won't). Now look at the objects you posted. Object C is not rotationally symmetric because you'd have to turn it ALL the way around before it looked the same as it did to start with (Object C is, however, symmetric about the vertical midline). Object A is also not rotationally symmetric , but you will see that if you had a cut-out piece of paper of Object B, and you turned it just half-way around (180 degrees) it would look exactly the same as it did at the beginning ... so Object B has rotational symmetry.

Answer 2

There can be no figure which doesn't have a rotational symmetry because every figure looks the same as at start after a 360 degree turn. There should be at least 1 rotational symmetry

Answer 3

As far as i can tell, only B appears to have rotational symmetry. What you are looking for is a shape that becomes self similar by a rotation other than 360 degrees, eg, if you rotate B by 180, you get B back.

Answer 4

b has rotational symmetry oder 2 the others are order 1

Answer 5

I don't know what they're called but B has 180 degree rotational symmetry about its centre.