Khan Academy: Linear Algebra: Using Orthogonal Change of Basis Matrix Example

Video defining an orthogonal matrix as a square matrix C whose columns form an orthonormal set. Shows that C will be invertible and that multiplying C transpose by C will result in the identity matrix. The result that C transpose equals the inverse of C is used later in the video in an example where C is formed from three specific vectors from an orthonormal set that are used to construct a linear transformation. C is used as a change of basis matrix to find a transformation matrix. [27:04]