Lecture
This lecture covers the concept of a direct frame in vector calculus, where a vector is defined as a directed line element with specific properties, and a frame is a geometric entity composed of three linearly independent vectors attached to a point. The lecture explains the characteristics of a direct frame, including orthonormal frames and the rules of the right-hand rule and corkscrew rule. It also delves into the properties of vectors in a direct frame and their orientation. The instructor emphasizes the importance of understanding these fundamental concepts in vector calculus.