How many sides does a circle have?

[Ravingstarfish]

Just that really. My sons tutor has taught him this and several people have said she’s wrong.... so how many sides does a circle have?

Thanks, 9toenails - it's impressive how knowledgeable MNetters are. I would say that for every person who posts with some expertise there will always be another MNetter along soon who knows even more, but that would require the number of MNetters to be infinite. I don't think we're quite that big yet...

What happened to the other toe nail? (did an angel steal the tenth one ?)

Bloody hell! I only stopped for food and wine and all hell has broken loose! It's all far over my head, but if I ever encounter any angels doing jiggery-pokery with chests and coins I won't trust the buggers an inch

DadDadDad: What happened to the other toe nail? (did an angel steal the tenth one hmm ?)

I do not want to tell the full story for fear of outing myself, but strangely, when I last checked the diseased toe, it looked as though there were ten little nailets just starting to grow at the end where the nail used to be. Ugh. Gross.

Now I just looked again and oh no! one of those little nailets seems to have dropped off already. Angels, huh?

Interestingly, I was examining my toenails just now under my infinity light. When this light is switched on, it automatically switches off after half a minute. A quarter of a minute later it switches on again, then (you guessed!), an eighth of a minute later, off it goes again. After another sixteenth of a minute, on it goes . . . and so on and so on; on, off, on, off, at ever decreasing intervals, each interval exactly half the previous one. Neat light, hein?

I recall I switched this light on at exactly midnight. Then I went straight to sleep. I wonder, now, whether the light was on or off at 12:01am. Hmm. What do you think, DadDadDad and others?

Off because all that on and off stuff would have driven me mad and I'd have removed the bulb ;)

The Circle line has 12 (I think).

9toenails - ah, so you inherited James Thomson's lamp

Weird coincidence after all my coins and angels stuff that your feet seem to be exhibiting 10:1 behaviour.

Inspired by this thread, I've taken my life in my hands and started another thread about infinity:

www.mumsnet.com/Talk/_chat/3601017--Maths-Can-one-infinity-be-bigger-than-another?watched=1

A circle is a shape. It is not a polygon BECAUSE it has no straight edges. It is often printed as a polygon with minute straight edges and you can certainly say that as n tends to infinity then the shape tends to a circle but it is not a circle.

The square root of a number is defined to be positive. Hence the square root of 9 is 3. However if you square a number to get 9, the numbers are 3 and -3. They are not technically inverses of each other and if taught as such, cause problems with post 16 maths and university level maths. We have highlighted this with the exam boards with evidence but no responses.

There are a infinite number of infinities as infinity is not a number, it's a word defined to mean a set of numbers that does not end. Whatever your biggest number, I can always find one bigger by doubling, squaring or even by adding 1.

Surely, a square root of 9 is 3, because -3 is the other square root. I agree that the square root function (on a calculator) finds the positive square root, which for positive real numbers is the inverse of squaring.

Then again, 8 has three cube roots, but only one of them is a real number.

infinite is infinite. there isnt a case that one infinite is bigger than the other infinite.

I'm afraid you're wrong. The set of integers is infinite and is bigger than the set of even numbers which is also infinite

There is no wrong there is no right a circle only has one side -Travis, side

Still not 100% convinced, but your last reply did really help! It's like that spinning dancer illusion: it seems to be completely different depending on the way you look at it (still not sure why it's not 9, 18, 27, 36, 45, 54....

That's what I would have thought too tbh. Add 10 every day, minus 1 every night, follows the 9 times table.

infinite is infinite. there isnt a case that one infinite is bigger than the other infinite.

I'm afraid you're wrong. The set of integers is infinite and is bigger than the set of even numbers which is also infinite

Actually, both of those are wrong. The set of integers is exactly the same size as the set of even numbers.

However, there are sets that are bigger in a well-defined way than the of integers. An example of such a set is the set of all infinite sequences of integers.

Both the above are well-established results in mathematics.

but '-infinity' is smaller than 'infinity'. i forgot to say that.

sorry i meant infinite instead of infinity.