A thin-walled steel tube having an elliptical cross section with constant thickness t (see figure) is subjected

Question:

A thin-walled steel tube having an elliptical cross section with constant thickness t (see figure) is subjected to a torque T = 18 k-in.
Determine the shear stress T and the rate of twist (in degrees per inch) if G = 12 ( 106 psi, t = 0.2 in., a = 3 in., and b = 2 in. (See Appendix D, Case 16, for the properties of an ellipse.)