text: let first=circleArea(7);
  let second=circleArea(1.5);
  let third=circleArea(20);
  
  function circleArea(r) {
    let area= r * r * Math.PI;
    return area;
  }
  document.write("r=7;" + "\n" + "area=" + "\n" + first);
  document.write("<br>");
  document.write("r=1.5;" + "\n" + "area=" + "\n" + second);
  document.write("<br>");
  document.write("r=20;" + "\n" + "area=" + "\n" + third);