Geometry similarity and dilations question help (please show work it helps me understand better)

Seth is using the gure shown below to prove Pythagorean Theorem using triangle similarity. In the given triangle ABC, angle A is 90 and segment AD is perpendicular to segment BC. Part A: Identify a pair of similar triangles. (2 points) Part B: Explain how you know the triangles from Part A are similar. (4 points) Part C: If DB = 9 and DC = 4, find the length of segment DA. Show your work. (4 points)