Looking over a proof of something, I was confused at this step: We end up with: R[tex]^{T}[/tex] R = I (the identity matrix) This must mean that R[tex]^{-1}[/tex] = R[tex]^{T}[/tex] This is confusing me because I know that A A[tex]^{-1}[/tex] = I , but in the R case the transpose is on the left side instead of the right, and it seems to me that it matters what order the matrices are multiplied.