9.Why do we use Use-Case diagram in object-oriented development? Draw a Use- Case diagram for an online course registration system.
![UML use case diagram examples for online shopping of web customer actor with top level use cases View Items, Make Purchase and Client Register, other use cases are Customer Authentication, View Recommended UML use case diagram examples for online shopping of web customer actor with top level use cases View Items, Make Purchase and Client Register, other use cases are Customer Authentication, View Recommended](https://www.uml-diagrams.org/examples/use-case-example-online-shopping-checkout.png)
UML use case diagram examples for online shopping of web customer actor with top level use cases View Items, Make Purchase and Client Register, other use cases are Customer Authentication, View Recommended
![UML use case diagram examples for online shopping of web customer actor with top level use cases View Items, Make Purchase and Client Register, other use cases are Customer Authentication, View Recommended UML use case diagram examples for online shopping of web customer actor with top level use cases View Items, Make Purchase and Client Register, other use cases are Customer Authentication, View Recommended](https://www.uml-diagrams.org/examples/use-case-example-online-shopping-view.png)