A solid compound shaft AD$,$ attached to a wall, consists of three segments with different materials: aluminium, bronze and steel. Two torques TB $=6\mathrm{.}0$ kNm and TD $=1\mathrm{.}5$kNm are applied on the compound shaft, as shown in Figure $2.$

a$)$ Draw the free body diaqramand verify that the reaction torque at $A$ is $4\mathrm{.}5$ Km$.$

b$)$ Draw the free body diaqram and determine the respective internal torques in segment shear stress developed in $AB.$

d$)$ Find the angle of twist in angle between A and $B.$ Given that Galuminium$=25$ GPa.