1. The diagram shows a sector $OAPB$ of a circle, centre $O$

$AB$ is a chord of the circle.

Angle$AOB=80^{\circ}$

The area of sector $OAPB$ is $\frac{25}{2} \pi {cm}^{2}$

Work out the perimeter of the shaded segment.
Give your answer correct to 3 significant figures.

......................$cm$