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\includegraphics[max width=\textwidth, alt={}, center]{afecdb38-c372-480a-9d6d-fafe6a371dc2-2_664_623_904_760} A uniform circular disc has mass \(4 m\), radius \(2 a\) and centre \(O\). The points \(A\) and \(B\) are at opposite ends of a diameter of the disc, and the mid-point of \(O A\) is \(P\). A particle of mass \(m\) is attached to the disc at \(B\). The resulting compound pendulum is in a vertical plane and is free to rotate about a fixed horizontal axis passing through \(P\) and perpendicular to the disc (see diagram). The pendulum makes small oscillations.

1. Find the moment of inertia of the pendulum about the axis.
2. Find the approximate period of the small oscillations.