Proving Tan Npi Y Tan Y

Proving tan(npi+y)=tan(y)

graph TB A[Proving tan(npi+y)=tan(y)] B[Understand the problem] C[Identify knowns] D[Identify unknowns] E[Formulate a plan] F[Execute the plan] G[Verify the results] A --> B A --> C A --> D A --> E A --> F A --> G B --> H{Do I understand the problem?} C --> I{What do I know?} D --> J{What do I need to find out?} E --> K{How can I solve this?} F --> L{Implement the solution} G --> M{Did I get the right answer?}