In a right-angled triangle ABC, ∠ABC = 90°, AB = 5 cm and BC = 12 cm. The radius of the circumcircle of the triangle ABC is

$mathrm{AC}=$ Diameter of circum circle $=sqrt{5^{2}+12^{2}}=13 mathrm{~cm}$

$herefore$ Circum-radius $=frac{13}{2}=6.5 mathrm{~cm}$