(i) All circles are .......... (congruent, similar).
(ii) All squares are .......... (similar, congruent).
(iii) All .......... triangles are similar (isosceles, equilaterals):
(iv) Two triangles are similar, if their corresponding angles are .......... (proportional, equal)
(v) Two triangles are similar, if their corresponding sides are .......... (proportional, equal)
(vi) Two polygons of the same number of sides are similar, if (a) their corresponding angles are and (b) their corresponding sides are .......... (equal, proportional).