1. The problem statement, all variables and given/known data The rotation matrix below describes a beam element which is rotated around three axes x,y and z. Derive the rotation matrix. 2. Relevant equations - 3. The attempt at a solution I can see where the x-values (CXx CYx CZx) come from. They're just the projections of the rotated x-axes (the one with rotation alpha and beta). But I don't understand how the rest is derived can somebody help me?