Question $3)$ A triaxial test was conducted on sandy clay. The test results are as follows; cu$\_$u$=3$ tm$^2\_$u$=20^$ Determine; a$)$ the deviator stress at failure $(\backslash$Delta $\backslash$sigma $\_$i$)$; and major principal stress if minor principal stress is equal to $\backslash$sigma $\_3,1\mathrm{.}5$ kg $/$ cm$^2$ b$)$ the normal stress and the shear stress on the failure plane c$)$ maximum shear stress on the sample and shear strength on this plane