Just as a spy will choose an Italian passport when traveling to Italy, we choose the identity that applies to the given scenario when solving a trigonometric equation. The trigonometric identities act in a similar manner to multiple passports-there are many ways to represent the same trigonometric expression.
However, we know that each of those passports represents the same person. In espionage movies, we see international spies with multiple passports, each claiming a different identity. Figure 1 International passports and travel documents
