how to calculate circle area code example

Example 1: area of circle

R = (3.14*r*r);

Example 2: area of circle

Area of circle = Pi * r^2 (r stands for radius and ^2 means squared)

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
}