The cross section of a brass tube is an equilateral triangle with a constant wall thickness, as shown in the figure. If the shear stress is limited to 8 ksi and the angle of twist is not to exceed 2 per foot length, determine the largest allowable torque that can be applied to the tube. Use G = 5.7 x 106 psi for brass. in. 16 Ada 1.5 in. FIG. P3.68