Ordem e Progresso LP II exerçício

<canvas width="600" height="400" ></canvas>
    <script>

        var tela = document.querySelector('canvas');
        var pincel = tela.getContext('2d');

        pincel.fillStyle = 'green';
        pincel.fillRect(100, 100, 400, 270);

        pincel.fillStyle = 'yellow';
        pincel.beginPath();
        pincel.moveTo(303,115);
        pincel.lineTo(115,235);
        pincel.lineTo(480,235);
        pincel.fill();

        pincel.fillStyle = 'yellow';
        pincel.beginPath();
        pincel.moveTo(305,355);
        pincel.lineTo(115,235);
        pincel.lineTo(480,235);
        pincel.fill();

        pincel.fillStyle = 'darkblue';
        pincel.beginPath();
        pincel.arc(304,235,75,0,2*3.14);
        pincel.fill();

    </script>