In today’s world software development industry and researchers has rapidly accepted the object-orientation paradigm for large scale system design. The object oriented language features of encapsulation, information hiding, inheritance, and polymorphism, promote concepts of modularity, reusability, and maintainability. If we are to capitalize on the potential advantages of object-orientation then it is important that the object-oriented approach is adopted and supported throughout the software development process. However the advantages of object-orientation cited above become potential disadvantages when we consider testing. Nowadays, it is clear that object-oriented paradigm, although provides many profitable features, requires special testing support and also provides opportunities for exploitation by a testing strategy. The majority of research is concerned with analysis, design and programming techniques. Software testing techniques have not kept pace with advances in object oriented system programming. The goal of this paper is to examine the testing of object oriented software and to derive test cases using equivalence partitioning and boundary value analysis technique for triangle problem.