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)

State whether the following quadrilaterals are similar or not :

In figure, (i) and (ii), DE || BC. Find EC in (i) and AD in (ii).

E and F are points on the sides PQ and PR respectively of a △PQR. For each of the following cases, state whether EF || QR :

(i) PE = 3.9 cm, EQ = 3 cm, PF = 3.6 cm and FR = 2.4 cm

(ii) PE = 4 cm, QE = 4.5 cm, PF = 8 cm and RF = 9 cm

(iii) PQ = 1.28 cm, PR = 2.56 cm, PE = 0.18 cm and PF = 0.36 cm