To find the length of arc, we can use the formula

The radius (r) is half of PS, hence

To find the angle:

The Sum of angles in a point will give us

Collecting like terms, we have

Therefore, the angle of arc RPT can be given as

Therefore, we find the length of the arc given we have all the parameters needed.
Hence,

Therefore, the length of the arc RPT is 50.8 feet to the nearest tenth.