The Steiner Deltoid as the Tangent Envelope of Wallace–Simson Lines
A Ramos et al
In unit-circumcircle coordinates, the deltoid has an explicit complex parametrisation. We prove its derivative formula and an equality of sets between the appropriate Wallace–Simson line and the tangent line.
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The Steiner Deltoid as the Tangent Envelope of Wallace--Simson Lines in Isabelle/HOL
The Steiner Deltoid as the Tangent Envelope of Wallace--Simson Lines in Isabelle/HOL in the Archive of Formal Proofs
