Can anybody prove this?

Question

how can we prove that the area of a circle is 22/7 r^2 and it's perimeter is 2*22/7*r?

Answer 1

Nobody can, because it's wrong. You can't "prove" something that's wrong.

The area of a circle is (3.14159265359... ) times r^2.

22/7 = 3.142857143...
This is not equal to the magic number pi; the 4th digit and all the rest are wrong.

Answer 2

Have a look at

http://www.mathreference.com/geo,circle.html

. . . but remember that 22/7 is just an approximate vaule for π (pi), so as pointed out by someone else, you can only prove that Area = πr², not that Area = 22/7 r²

Showing that Perimeter = 2πr is more difficult, and most proofs use calculus together with radians for angle measurement rather than degrees - I would give that one a miss at the moment.

Answer 3

There are two separate questions here.

1. Show that there is a number pi such that the area of a circle is pi r^2 and the circumference is 2 pi r.

2. Calculate or estimate pi.

I suggest that you not worry much about either of those until you study calculus. Answers that superficially don't involve calculus really turn out to just be "doing calculus badly".

Answer 4

area of circle is pi r^2
pi=22/7
therefore area of circle= 22/7r^2
we know that perimeter of circle is pi*d where d is diameter of circle. so pi=22/7 and is 2r
therefore perimeter of circle=2*22/7*r

Answer 5

22/7 = 3.14285714285... and pi = 3.14159265359...

if you take only the two first numbers after the point, this is:

22/7=3.14 and pi = 3.14

so, only in this case:

3.14=3.14 and 22/7=pi.

I read you later.

Answer 6

Nobody can!
B'coz u r wrong.
It's pie * R^2
and pie does not have an exact value. It's not 22/7
It's actually between 22/7 and 223/71.
So............. You are wrong .

Answer 7

1st : you can prove that by using the formula which is 2 into bie into the radius..

Answer 8

use differential calculus
use the derivative of a function

Answer 9

sry i cant im too slow!