The cross section of a thin tube having variable wall thickness t is shown in figure 1a. The median line of the cross section is a circle of radius r, and the thickness is given by the following equation: 1-6(1+3=124) ㅁ을) where to is the thickness at the section where 0 = 0. If the tube is subject to a torque T, what is the maximum shear stress Tmax? What is the minimum shear stress Tmin? What is the angle of twist per unit length? 1 21 Figure la x to