If the question is asking the radius of 'the circle' S, then we need to pick a point on the circle and measure its distance from the center.
In this case, we already have G picked for us and S is the center. So, GS is our radius. It is also written that GS is equal to 6.1. This means the length of the radius of the circle S is 6.1.
Another way of finding it is; as you can see from the picture, YL is a line which goes through the point S or the center. We call those lines a 'diameter'. Diameters also equal to two times of the radius.
So, we know that our diameter is 12.2, when we divide that by 2 we got:
![(12.2)/(2) = 6.1](https://img.qammunity.org/2019/formulas/mathematics/middle-school/3baq438e23en7kntnc5yjpsuyqt9gkr027.png)
as our radius.