How do you find the area of a circle without using pi?

Answer 1

You cannot get an accurate measure of the area without pi.

If you are interested in an approximation, you could divide the circle up into tiny squares of some fixed area (their size would depend on how big the original circle was). Then count the number of squares where half or more is inside the circle and multiply by the area of each square. That will give you an estimate of the area of the circle.

You could make an approximation with inscribed and circumscribed polygons (which are the sum of a number of isosceles triangles) and average the two areas, increasing the number of sides of the polygons to increase accuracy (that is the way the early Greek mathematicians did it).

Much easier and quicker to use pi!