Q$-7$: A consolidated$-$drained tri$-$axial test was conducted on a normally consolidated clay. The results are as follows: confining stress ${}_3=250k\frac{N}{m^2}$ and deviator stress $({}_d)r=150k\frac{N}{m^2}.$ Determine $($i$)$ angle of friction, ${}^{\text{'}},($ii$)$ angle $$ that the failure plane makes with the major principal plane, $($iii$)$ find the normal stress ${}^{\text{'}}$ and the shear stress ${}_f$ on the failure plane, and $($iv$)$ determine the effective normal stress on the plane of maximum shear stress. $2\mathrm{.}5+2\mathrm{.}5)$