A generator supplying an electrical power given by Pe $=2\mathrm{.}5$ sin $$ p$.$u$.$ to infinite busbar. The input mechanical power drive the generator Pm$=1$ p$.$u$.$ If the mechanical drive change from $1$ to $1\mathrm{.}5$ p$.$u$.$ and the load angle increases until reached maximum value of $60$ find: i$)$ the equilibrium angle $$o ii$)$ The energy areas A$1$ & A$2$ after Pm changes iii$)$ Is the system stable or not