Which of the following pairs of angles are vertical angles? (There may be more than one answer)

When two lines intersect, four angles are formed. There are two pairs of nonadjacent angles. These pairs are called vertical angles.

So, the opposite angle is the same.

∠2 = ∠4 , ∠5 = ∠7, ∠1 = ∠3 , ∠8 = ∠6