# Meeting Details

Title: Making invisible geometric objects Geometry Luncheon Seminar Gregory Galperin, Eastern Illinois University In my talk, I will show some examples of invisible geometric objects''. This means that light bends around the object, causing it to become as if it were invisible. When designing such objects, the billiard law of reflection will play a crucial role. The main example in my talk will concern the billiard reflection in ellipses and hyperbolas. To prove that the reflection in my design is indeed _billiard_, it is necessary to prove a tricky lemma about the angle bisector of a triangle. If time permits, I will provide a proof of this lemma. All necessary definitions and explanations will be given during the talk.