who discovered formula for area of a circle
Area of a circle One method of deriving this formula, which originated with Archimedes, involves viewing the circle as the limit of a sequence of regular polygons. The area of a regular polygon is half its perimeter multiplied by the distance from its center to its sides, and the corresponding formula (that the area is half the perimeter times the radius, i.e. ​1⁄2 × 2πr × r) holds in the limit for a circle.
Pi The symbol used by mathematicians to represent the ratio of a circle's circumference to its diameter is the lowercase Greek letter π, sometimes spelled out as pi, and derived from the first letter of the Greek word perimetros, meaning circumference.[7] In English, π is pronounced as "pie" (/paɪ/, paɪ).[8] In mathematical use, the lowercase letter π (or π in sans-serif font) is distinguished from its capitalized and enlarged counterpart ∏, which denotes a product of a sequence, analogous to how ∑ denotes summation.