Question 877005
The center and the five points on the circle form five isosceles triangles.  The one tip angle of each triangles is 360/5=72 degrees, and the two equal sides of each triangle are PU=10 cm. each.


What this question really seems to need is that from P to S is 3/5 the way around the circle, and that you already have the radius, PU=10, and can take 3/5 of the circumference.  That seems to be all that you need.


With that, Arc PS is {{{(3/5)*(2pi*10)=highlight(12pi)}}} centimeters.