### Fundamental Mathematics: Rotation & Reflection in three dimensional space

We use matrices, eigenvalues and eigenvectors to solve the following: Let f be the rotation in the 3-dimensional space about the x-axis through the angle pi/2 and g be the rotation about the y-axis through the same angle. Describe the rotation f g. Let h be the reflection in the plane orthogonal to the vector 2i - j + 3k. D