Definition:Double Tangent

Definition

A double tangent is a pair of tangent lines to the same locus whose points of tangency coincide.

This happens at a double point

Also defined as

The term double tangent is also used for the concept of the bitangent, but $\mathsf{Pr} \infty \mathsf{fWiki}$ we keep the concepts separate.

Also see

• Definition:Double Point

• Results about double tangents can be found here.

Sources

• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): double tangent: 2.
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): double tangent: 2.