<canvas width="600" height="400" > </canvas>
<script>
var pantalla = document.querySelector("canvas");
var pincel = pantalla.getContext("2d");
pincel.fillStyle= "lightgrey"
pincel.fillRect(0, 0, 600, 400);
pincel.fillStyle= "green"
pincel.fillRect(0, 0, 200, 400);
pincel.fillStyle= "red"
pincel.fillRect(400, 0, 200, 400);
pincel.fillStyle= "yellow";
pincel.beginPath();
pincel.moveTo(300,200);
pincel.lineTo(200,400);
pincel.lineTo(400,400);
pincel.fill();
pincel.fillStyle= "blue";
pincel.beginPath();
pincel.arc(300,200,50,0,2*3.14)
pincel.fill();
</script>
