In the context of business analysis, a requirements viewpoint refers to a perspective or lens through which requirements are formulated and understood. A use case is an example of a requirements viewpoint because it represents a sequence of actions, typically involving an actor and a system, to achieve a goal. Use cases are used to capture functional requirements and describe how users will interact with a solution. Reference: The BABOK Guide mentions use cases as a tool within the requirements analysis and design definition, which aligns with the concept of a requirements viewpoint1.