<svg id="trie2" height="300" width="300">
    <polygon fill="rgba(0, 255, 0, 0.5)" points="150,0 20,225 280,225"></polygon>
    <circle cx="150" cy="150" fill="transparent" r="150" stroke="black" stroke-dasharray="2, 2" stroke-width="1"></circle>
</svg>

filter: blur(5px);