Circle has infinite sides how many sides does a semi circle have?

1. Oct 11, 2008

Noj Werdna

If a circle has infinite sides how many sides does a semi circle have?
i have asked my teachers at school but they have ll said u wud have 2 divide infinity by 2 and +1 which obviously isnt possible cos infinity isnt reli a number is it...

Thanks

2. Oct 11, 2008

scottie_000

Re: Circles!!!

A circle is said to have infinitely many "sides" due to the analogy with regular polygons.
(i.e. a triangle has 3, a square 4, and so on)
Eventually you get a shape with so many sides that it "becomes" a circle.
If you want to find how many "sides" a semicircle has, just continue in the same way...
Cut regular polygons in half and work out how many sides they have
(i.e. half a triangle has 3 sides half a square has 4, half a pentagon.... etc)

Do you see the idea?

(It's just a bad/weird definition of a circle, since it doesn't really have sides, does it?)

3. Oct 11, 2008

Cvan

Re: Circles!!!

Any curve can be looked at as having an infinite number of 'sides' whose length goes to zero, no matter how big.

4. Oct 11, 2008