State which pairs of triangles in the figure given below are similar. Write the similarity rule used and also write the pairs of similar triangles in symbolic form (all lengths of sides are in cm):

If △ABC ~ △PQR, perimeter of △ABC = 32cm, perimeter of △PQR = 48cm and PR = 6cm, then find the length of AC.

If in two right triangles, one of the acute angle of one triangle is equal to an acute angle of the other triangle, can you say that the two triangles are similar? Why?

If △ABC ~ △DEF, AB = 4 cm, DE = 6 cm, EF = 9 cm and FD = 12 cm, then find the perimeter of △ABC.