how to get the area of a circle code example

Example 1: calculate area of circle

import math
r = 50
a = r**2*math.pi
print(a)

Example 2: area of a circle

def circle(radius):
	return radius * math.pi * 2

Example 3: calculate area of circle

3.14 * radius * radius = area

Example 4: calculate area of circle

function calcAreaOfCircle(radius){
    return Math.PI * r **2
}
function calcAreaOfCircle(diameter){
  return Math.PI * (diameter / 2) **2
}