The Systems Development Life Cycle (SDLC) model may not be an appropriate methodology in IT application development situations where the system specifications are not well defined or when the problem to be solved is an ‘ad-hoc’ problem with a very low probability of reoccurrence. Approaches such as Rapid Application Development (RAD) and Agile Development have been found to be more suitable for these situations. Discuss the basics of what these approaches are and how they work. Also, summarize the advantages and disadvantages of RAD and Agile Development.