$3\mathrm{.}135$ A $1\mathrm{.}25-m-$long steel angle has an L$127766\mathrm{.}4$ cross section.

From Appendix E we find that the thickness of the section is $6\mathrm{.}4$ mm

and that its area is $1250m{m}^2.$ Knowing that ${}_{\text{a}\text{l}\text{l}}=60$MPa and that

$G=77\mathrm{.}2$GPa, and ignoring the effect of stress concentrations, deter$-$

mine $($a$)$ the largest torque $T$ that can be applied, $($b$)$ the correspond$-$

ing angle of twist.

Fig. P$3\mathrm{.}135$