bandeira

<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, 0); 
    pincel.lineTo(50, 200);  
    pincel.lineTo(400, 200);
    pincel.lineTo(550, 200);
    pincel.fill();

    pincel.fillStyle = "yellow";
    pincel.beginPath();
    pincel.moveTo(300, 400); 
    pincel.lineTo(50, 200);  
    pincel.lineTo(400, 200);
    pincel.lineTo(550, 200);
    pincel.fill();

    pincel.fillStyle = "blue";
    pincel.beginPath();
    pincel.arc(300, 200, 100, 0, 2*3.14);
    pincel.fill();

</script>