Calculate arc measure: Calculate the measure of the arc mRS if it is a semicircle. Since a semicircle is half of a circle, the measure of the arc is half of 360 degrees. Calculation: 2360=180 degrees.
Check if semicircle: Check if the given arc mRS is indeed a semicircle. If it is, then the calculation in the previous step is correct. If not, additional information is needed to proceed.