1. Fill in the blanks using the correct word given in brackets :
(i) All circles are ____ . (congruent, similar)
(ii) All squares are ____ . (similar, congruent)
(iii) All ____ triangles are similar. (isosceles, equilateral)
(iv) Two polygons of the same number of sides are similar, if (a) their corresponding angles are ____ and (b) their corresponding sides are ____ . (equal, proportional)