Intentado hacer la escuadra

<meta charset="UTF-8">
<h2>Escuadra </h2>
<canvas width="600" ; height="400">
</canvas>
<script>
    var pantalla = document.querySelector("canvas");
    var pincel = pantalla.getContext("2d");

    pincel.beginPath();
    pincel.strokeStyle = 'black';
    pincel.moveTo(50, 50);
    pincel.lineTo(50, 400);
    pincel.stroke();

    pincel.beginPath();
    pincel.strokeStyle = 'red';
    pincel.moveTo(50, 400);
    pincel.lineTo(400, 400);
    pincel.stroke();

    pincel.beginPath();
    pincel.strokeStyle = 'blue';
    pincel.moveTo(50, 50);
    pincel.lineTo(400, 400);
    pincel.stroke();

    pincel.beginPath();
    pincel.strokeStyle = '    #CC00CC';
    pincel.moveTo(100, 175);
    pincel.lineTo(100, 350);
    pincel.stroke();

    pincel.beginPath();
    pincel.strokeStyle = '#000033';
    pincel.moveTo(100, 350);
    pincel.lineTo(275, 350);
    pincel.stroke();

    pincel.beginPath();
    pincel.strokeStyle = '#FF6633';
    pincel.moveTo(100, 175);
    pincel.lineTo(275, 350);
    pincel.stroke();

</script>