What is the inverse of a translation by vector v⃗=⟨a,b⟩\vec{v} = \langle a, b \ranglev=⟨a,b⟩?
A translation by ⟨−a,−b⟩\langle -a, -b \rangle⟨−a,−b⟩
A translation by ⟨a,b⟩\langle a, b \rangle⟨a,b⟩
A reflection across the vector v⃗\vec{v}v
A rotation by 180∘180^\circ180∘