Capitalizing trigonometric functions like Sinθ and Cosθ is not common practice, but it may indicate a specific convention or context. While it does not change the fundamental meaning of the functions, some texts use capitalized forms to denote restricted domains or complex extensions. There is some confusion regarding the use of capital letters, as different authors may apply them for various definitions. The discussion highlights the lack of consensus on this topic, with no definitive sources supporting the capitalization claim. Ultimately, the choice to capitalize trigonometric functions varies by author and context.