Learn to apply sum and difference formulas in trigonometry through a comprehensive 58-minute video lecture. Explore techniques for finding angles using inverse trigonometric functions, unit circle applications, and proofs of phase shift identities for sine and cosine. Dive into practical examples demonstrating the use of these formulas for cosine, sine, and tangent functions. Gain a deeper understanding of identity formulas and their applications in solving complex trigonometric problems. This in-depth tutorial, presented by Professor Leonard, covers essential topics in precalculus trigonometry, providing a solid foundation for advanced mathematical concepts.