<canvas width="500" height="300"></canvas>
<script>
var tela = document.querySelector("canvas");
var pincel = tela.getContext("2d");
pincel.fillStyle = "green"
pincel.fillRect(0, 0, 500, 300);
pincel.fillStyle = "Yellow"
pincel.beginPath();
pincel.moveTo(250, 0);
pincel.lineTo(0,150);
pincel.lineTo(500,150);
pincel.fill();
pincel.fillStyle = "Yellow"
pincel.beginPath();
pincel.moveTo(250,300);
pincel.lineTo(500,150);
pincel.lineTo(0,150);
pincel.fill();
pincel.fillStyle = "DarkBlue"
pincel.beginPath();
pincel.arc(250, 150, 100, 0, 2*3.14);
pincel.fill();
</script>
