<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width,initial-scale=1.0">
<title>Document</title>
</head>
<body>
<script>
var num1 = prompt("请输入圆的半径")
if(!isNaN(num1)){
var sum = parseFloat(num1)*Math.PI*2
var sum1 = parseFloat(num1)*parseFloat(num1)*Math.PI
console.log(sum.toFixed(2));
console.log(sum1.toFixed(2));
}
else{
alert("输入正确的值")
}
</script>
</body>

