no goals
E : Type u_1
inst✝ : SeminormedCommGroup E
ε δ : ℝ
s t : Set E
x✝ y : E
hs : IsCompact s
hδ : 0 ≤ δ
x : E
⊢ s * closedBall x δ = x • cthickening δ s
rw [← smul_closedBall_one, mul_smul_comm, hs.mul_closedBall_one hδ]