The oblique asymptotes of some historically well-known curves such as the cissoid of Diocles and the folium of Descartes. The aim of Delving Deeper is for teachers to pose and solve novel math problems, expand on mathematical connections, or offer new insights into familiar math concepts. Delving Deeper focuses on mathematics content appealing to secondary school teachers. It provides a forum that allows classroom teachers to share their mathematics from their work with students, their classroom investigations and products, and their other experiences. Delving Deeper is a regular department of Mathematics Teacher.