<!DOCTYPE html>
<html>
<head>
<title>Рисунок</title>
</head>
<body bgcolor="LightGreen">
<h1>Это canvas</h1>
<canvas id="namevasya" width="1500" height="1000" style="background: LightCyan;"></canvas>
<script>
var canvas = document.getElementById('namevasya');
var ct = canvas.getContext('2d');
var x = 200;
var y = 230;
var size = 1.1;
ct.beginPath();
ct.moveTo(x+600*size,y+200*size);
ct.lineTo(x+400*size,y+400*size);
ct.lineTo(x+800*size,y+400*size);
ct.lineTo(x+600*size,y+200*size);
ct.stroke();
ct.beginPath();
ct.moveTo(x+650*size,y+450*size);
ct.arc(x+600*size,y+450*size,50*size,0,2*Math.PI);
ct.stroke();
</script>
</body>
</html>