The document discusses the cross product of two vectors. Some key points: - The cross product requires both vectors to be three-dimensional and results in another vector, unlike the dot product which results in a number. - The formula for the cross product is derived using determinants. Two methods - using cofactors or copying columns - provide the formula. - The direction of the cross product follows the right-hand rule and is orthogonal to both original vectors, unless they are parallel. - The cross product can be used to find a vector orthogonal to a plane defined by three points, and to determine if three vectors lie in the same plane.