Answer:
S and U are centres of the respective circles.
a. Three radii of Circle S : SU , SR , ST
(Lines from the centre of the circle to its circumference)
b.Three radii of Circle U : US , UR , UT
(Lines from the centre of the circle to its circumference)
c.The radii of the two circles are equal to each other as they are congruent to each other.