FRIHOST FORUMS SEARCH FAQ TOS BLOGS COMPETITIONS
You are invited to Log in or Register a free Frihost Account!


Circle Math





startsomething
So a circle is a regular polygon with infinate sides. For the longest time people didn't believe me. So I tried to prove it to them. And this is what I came up with:

A=pi * r^2
A=1/2 * a * p (a = apothem or the distance from the center to perpendicular to an edge , p = perimeter)

a is the same as r
p is the same as C (circumference)
C is pi * D
and D is 2r
so....

A=1/2 * r * pi * 2 * r
A=pi * r^2

cool huh?
now I just have to figure out what pi is... really.
I think because circles have infinate sides, pi goes on forever. So does this mean that there is a constant like pi for every regular polygon, that is not infinate? hmmm....

Whatcha think?
ml
another cool thing about circles (i figured it out myself)

for the caculation of the perimeter of a circle, you approximate the circle by n isosceles triangles from the center to circumference.

for the outer side of one trinagle you get:

outer side = 2 * sin((angle in the center)/2) * r

for n triangles you get:

perimeter = 2 * r * n * sin(180/n)

then you go for the limit for n -> infinite

lim(n->inf) (2 * r * n * sin(180/n)) = 2 * r * lim(n->inf) (n * sin(180/n))

and guess what the last limit is! its PI Very Happy
Related topics
How many degrees are in a circle exactly
Math Equation Editor and Computer Algebra for Students
math and science jokes
Alegbra II math can't apply on Pre-Alegbra
an island and an ipod????
A math problem only the smart can solve
What does math ment for you?
sms jokes
sms jokes
Math Problem. 30 frih. (Solved!)
Chocolate Math...
Free SAT math help here
math problem with javascript
math equations
Reply to topic    Frihost Forum Index -> General -> General Chat

FRIHOST HOME | FAQ | TOS | ABOUT US | CONTACT US | SITE MAP
© 2005-2011 Frihost, forums powered by phpBB.