In the right triangle A B C, A C=12, B C=5, and angle C is a right angle. A semicircle is inscribed in the triangle as shown. What is the radius of the semicircle?
Answer Choices
A. \dfrac{7}{6}
B. \dfrac{13}{5}
C. \dfrac{59}{18}
D. \dfrac{10}{3}
E. \dfrac{60}{13}