∠3, ∠7, ∠6: angles congruent to ∠2
∠2 and ∠3 are vertical angles, ∠3 and ∠7 are corresponding angles, and ∠7 and ∠6 are vertical angles.
∠3, ∠7, ∠2: angles congruent to ∠6
∠2 and ∠3 are vertical angles, ∠3 and ∠7 are corresponding angles, ∠7 and ∠6 are vertical angles.
∠4, ∠8, ∠5: angles congruent to ∠1
∠1 and ∠4 are vertical angles, ∠4 and ∠8 are corresponding angles, ∠8 and ∠5 are vertical angles.