Q$2.$ The stresses on a failure plan in a Consolidated Drained test on a sand are as under:

Normal stress, ${}^{\text{'}}=100$kPa

Shear stress, $=40$kPa

a$.$ Draw the Mohr's circle and the Mohr$-$Coulomb failure envelope.

b$.$ Determine the internal friction angle and the angle which the failure plane makes with the major principal plane. $($Use both graphical and analytical method$).$

c$.$ Determine the major and the minor principal stresses $($Use both graphical and analytical method$).$