(a) Maximum bending stress occurs at inside fibre of sections with
ri=75mm (refer figure 4.5)

(b)	rn=(1/4)* (sqrt(ro) + sqrt(ri))^2
	=0.08705 m

(c)	e=R-rn =0.0004 m

(d)	Si=(M*hi)/(A*e*ri) =41.0 MN/m^2

(e)Maximum shear stress occurs at every point from A to B and from C to D
Maximum shear stress=20.5 MN/m^2