···················································
∢1 и ∢2, ∢2 и ∢4, ∢3 и ∢4, ∢1 и ∢3, ∢5 и ∢6, ∢6 и ∢8, ∢7 и ∢8, ∢5 и ∢7, — смежные — сумма смежных углов равна 180°.
∢1 и ∢4, ∢2 и ∢3, ∢5 и ∢8, ∢6 и ∢7 — вертикальные — равны между собой.
