For a soil element the strength properties are given as c $=50$kPa and $\backslash$Phi $=15$ degrees.

$3\mathrm{.}1$ Find $\backslash$sigma $1$ at failure if $\backslash$sigma $3=100$KPa.

$3\mathrm{.}2$ For the failure condition given in $($a$)$ find shear and normal stresses.

$3\mathrm{.}3$ Plot the Mohr$-$ Circle at failure.