A spherical shell of diameter d$($m$)$ and wall thickness t$($cm$)$ is

subjected to an internal pressure of p$($N$/$mm$2$

$).$ Determine the

biaxial stresses $(\backslash$sigma x$,\backslash$sigma y$)($N$/$mm$2$

$)$ on an element of the shell. Also

determine the Principal Stress $\backslash$sigma n and the angle $\backslash$phi n made by the

Principal plane. Given P$=76/15,$d$=3,$ t$=3$