Area of a Circle: Find Proof of πr2 Formula

In summary, the formula for finding the area of a circle is &pi;r<sup>2</sup>. It was discovered by ancient mathematicians through geometric proofs and calculations, with the most well-known proof attributed to Archimedes. The number &pi; represents the ratio of a circle's circumference to its diameter and is an irrational number. The formula works by multiplying the radius squared by &pi;, which is equivalent to adding up infinitely many infinitesimal triangles. Other methods for finding the area of a circle include using the diameter or circumference, as well as numerical methods like integrals.
  • #1
repugno
78
0
Hello all. Where can I find proof that the area of a circle can be calculated using the formula &pi;r2? Any response will be greatly appreciated, thank you.
 
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  • #2
I believe it can be done using a limit process. Cut the circle into n equal triangles and take the limit as n goes to infinity.
 
  • #3
And, of course, the area of a circle of radius R, with center at the origin of a coordinates system is the integral
&int;-RR2&radic;(R2- x2)dx. That gives &pi;R2 as the area.
 

1. What is the formula for finding the area of a circle?

The formula for finding the area of a circle is πr2, where π is a mathematical constant approximately equal to 3.14159 and r is the radius of the circle.

2. How was the formula for the area of a circle discovered?

The formula for the area of a circle was discovered by mathematicians in ancient times through geometric proofs and calculations. The most well-known proof is attributed to the Greek mathematician Archimedes, who used a method of exhaustion to approximate the area of a circle.

3. What is the significance of the number π in the formula?

The number π is a mathematical constant that represents the ratio of a circle's circumference to its diameter. It is an irrational number, meaning it cannot be expressed as a finite decimal or fraction, and has been calculated to over a trillion digits.

4. Can you explain how the formula for the area of a circle works?

The formula for the area of a circle works by taking the radius of the circle and squaring it, then multiplying it by the value of π. This is because the area of a circle is equal to the sum of infinitely many infinitesimally thin triangles with their bases on the circle's circumference and their height equal to the radius. By multiplying the radius squared by π, we are essentially adding up all of these infinitesimal triangles to find the total area of the circle.

5. Are there any other ways to find the area of a circle?

Yes, there are other formulas and methods for finding the area of a circle, such as using the diameter instead of the radius (A = πd2/4) or using the circumference (A = C2/4π). Additionally, there are numerical methods, such as using integrals, to approximate the area of a circle to a desired level of accuracy.

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