<!DOCTYPE html>
<html lang="pl">
<head>
<meta charset="utf-8">
<title></title>
</head>
<body>
<input type="number" id="xd"></input>
<button type="button" id="b1" onclick="be1()">pole</button>
<button id="b2" onclick="be2()">obwod</button>
<p id="ww"></p>
<script>
function be1(){
var a = parseInt(document.getElementById("xd").value);
if(isNaN(a)) {
document.getElementById("ww").innerHTML = "Należy wpisać wartość liczbową";
} else {
document.getElementById("ww").innerHTML = "P=a^2="+a*a;
}
}
function be2(){
var a = parseInt(document.getElementById("xd").value);
if(isNaN(a)) {
document.getElementById("ww").innerHTML = "Należy wpisać wartość liczbową";
} else {
document.getElementById("ww").innerHTML = "Obw = 4*a"+4*a;
}
}
</script>
</body>
</html>
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