Write the formula of work done by torque in a rotational rigid body about a fixed axis.

(N/A) For a rigid body rotating about a fixed axis,the work done $W$ by a torque $\tau$ through an angular displacement $d\theta$ is given by the integral of the torque over the angular displacement.
The infinitesimal work done is $dW = \tau \cdot d\theta$.
For a finite angular displacement from $\theta_1$ to $\theta_2$,the total work done is:
$W = \int_{\theta_1}^{\theta_2} \tau \, d\theta$.
If the torque $\tau$ is constant,the formula simplifies to:
$W = \tau (\theta_2 - \theta_1) = \tau \Delta \theta$.