Update Convex Hull.ipynb

ipynb/Convex Hull.ipynb

@@ -27,7 +27,7 @@
    "source": [
     "Pound a bunch of nails into a board, then stretch a rubber band around them and let the rubber band snap taut, like this:\n",
     "\n",
-    "<img src=\"http://www.personal.kent.edu/~rmuhamma/Compgeometry/MyCG/Gifs-CompGeometry/ch2.gif\">\n",
+    "<img src=\"convexhull.jpg\">\n",
     "\n",
     "The rubber band has traced out the *convex hull* of the set of nails. It turns out this is an important problem with applications in computer graphics, robot motion planning, geographical information systems, ethology, and other areas.\n",
     "More formally, we say that:\n",