grandes-ecoles 2013 QII.A.3

grandes-ecoles · France · centrale-maths2__psi Matrices Matrix Power Computation and Application
Let $n \in \mathbb{N}^*$. Let $A \in M_2(\mathbb{R})$ be an antisymmetric matrix. We set $A = \begin{pmatrix} 0 & -\alpha \\ \alpha & 0 \end{pmatrix}$ where $\alpha \in \mathbb{R}$.
Deduce that $E(A)$ exists and that it is a rotation matrix, whose angle we shall specify.
Let $n \in \mathbb{N}^*$. Let $A \in M_2(\mathbb{R})$ be an antisymmetric matrix. We set $A = \begin{pmatrix} 0 & -\alpha \\ \alpha & 0 \end{pmatrix}$ where $\alpha \in \mathbb{R}$.

Deduce that $E(A)$ exists and that it is a rotation matrix, whose angle we shall specify.