∀ {𝕜 : Type u_1} {E : Type u_2} [inst : AddCommGroup E] [inst_1 : SMul 𝕜 E] [inst_2 : TopologicalSpace E] {s t : Set E}
  {x : E} [ContinuousAdd E], nhdsWithin x s ≤ nhdsWithin x t → tangentConeAt 𝕜 s x ⊆ tangentConeAt 𝕜 t x