Solution
= Solution
At first order, $\Lambda^T\eta\Lambda=\eta$ gives
$\omega^T\eta+\eta\omega=0$. Therefore
$$
\boxed{\omega_{\mu\nu}
=\eta_{\mu\rho}\omega^\rho{}_\nu
=-\omega_{\nu\mu}}.
$$
= Solution
At first order, $\Lambda^T\eta\Lambda=\eta$ gives
$\omega^T\eta+\eta\omega=0$. Therefore
$$
\boxed{\omega_{\mu\nu}
=\eta_{\mu\rho}\omega^\rho{}_\nu
=-\omega_{\nu\mu}}.
$$