Update index.html

Author: Gmac4247

index.html

@@ -4660,6 +4660,10 @@ <h3 itemprop="name" style="margin:12px">Volume of a horizontal square Frustum Py
 </div>
 	</div>
 <br>
+<figure class="imgbox">
+    <img class="center-fit" src="squareFrustum.jpeg" alt="Square frustum pyramid">
+</figure>
+<br>
 <p itemprop="description" style="margin:12px">The volume of a square frustum pyramid can be calculated via a simplified formula.</p>
 <br>
 <div style="margin:12px">