<canvas width="600" height="400"></canvas>
<script>
var tela = document.querySelector("canvas");
var pincel = tela.getContext("2d");
pincel.fillStyle = "green";
pincel.fillRect(0, 0, 600, 400);
pincel.fillStyle = "yellow";
pincel.beginPath();
pincel.moveTo(300, 50); //ponta superior
pincel.lineTo(550,200); //ponta direita
pincel.lineTo(300,350); //ponta inferior
pincel.lineTo(50,200); //ponta esquerda
pincel.fill();
pincel.fillStyle = "darkblue";
pincel.beginPath();
pincel.arc(300, 200, 100, 0, 2 * 3.14);
pincel.fill();
</script>
