Semi-perimeter of triangle (s) = \(\frac{3+4+5}{2}\)cm = 6 cm
∴ Area of triangle A = \(\sqrt{s(s-a)(s-b)(s-c)}\)
= \(\sqrt{6\times3\times2\times1}\) cm2 = 6 cm2
∴ Radius of circum-circle = \(\frac{abc}{4(\text{Area of}\,\Delta)}\) = \(\frac{3+4+5}{4\times60}\) cm = 2.5 cm
