$\Omega=\omega \sqrt{\theta_{0}^{2}-\theta^{2}}$
$\Omega=5 \pi \sqrt{\pi^{2}-\frac{\pi^{2}}{4}} \Omega=5 \pi \sqrt{\pi^{2}-\frac{\pi^{2}}{4}}$
$=\frac{5 \pi^{2} \sqrt{3}}{2}=42.7 \mathrm{rad} / \mathrm{s}$
$\mathrm{y}=\mathrm{A}_{0}+\mathrm{A} \sin \omega \mathrm{t}+\mathrm{B} \cos \omega \mathrm{t}$
Then the amplitude of its oscillation is given by