Escuadra
<meta charset = "UTF-8">
<canvas width="400" height="400"></canvas>
<script>
var pantalla = document.querySelector("canvas");
var pincel = pantalla.getContext("2d");
pincel.fillStyle = "white"
pincel.fillRect(0,0,400,400)
pincel.fillStyle = "black"
pincel.beginPath();
pincel.moveTo(50,50)
pincel.lineTo(50,400)
pincel.lineTo(400,400)
pincel.fill();
pincel.fillStyle = "white"
pincel.beginPath();
pincel.moveTo(100,175)
pincel.lineTo(100,350)
pincel.lineTo(275,350)
pincel.fill();
</script>
