<script>
let tela = document.getElementById("canvas");
let pincel = tela.getContext("2d");
pincel.lineWidth = 10;
pincel.beginPath();
pincel.moveTo(50, 50);
pincel.lineTo(50, 400);
pincel.lineTo(400, 400);
pincel.closePath();
pincel.stroke();
</script>
