Lecture
This lecture covers the continuity and differentiability of trigonometric functions, including the definition of derivative, slope of secant lines, interpretation of derivatives geometrically, and the derivative functions of sine, cosine, and tangent. It also introduces Leibniz notation, rules for deriving trigonometric functions, and the concept of inverse trigonometric functions. The instructor emphasizes the importance of understanding the derivative of trigonometric functions for further mathematical applications.