Triangles

In triangle ABC, if DE is parallel to BC and AD = 6 cm, DB = 9 cm, AE = 4 cm, then find EC.

If triangles ABC and DEF are similar with ratio of similarity 3:4, and the area of triangle ABC is 27 cm², find the area of triangle DEF.

In triangle PQR, if angle P = 60°, angle Q = 80°, and in triangle XYZ, angle X = 60°, angle Y = 80°, then which similarity criterion proves that triangle PQR ~ triangle XYZ?

Which of the following sets of measurements can form similar triangles? (Multiple correct answers possible)