<canvas width="500" height="400" ></canvas>
<script>
var tela = document.querySelector("canvas")
var pincel = tela.getContext("2d")
pincel.fillStyle = 'green'
pincel.fillRect(0,0, 500, 400)
pincel.fill()
pincel.fillStyle = 'yellow'
pincel.beginPath()
pincel.moveTo(250, 50)
pincel.lineTo(50, 200)
pincel.lineTo(250, 350)
pincel.lineTo(450, 200)
pincel.fill()
pincel.fillStyle = "darkblue"
pincel.beginPath()
pincel.arc(250, 200, 100, 0, 2*3.14)
pincel.fill()
</script>
