$[3]$ A two$-$dimensional plane triangular element is subjected to a linearly varying edge pressure and the weight as body force as shown in Figure. Evaluate the stiffness matrix and the consistent load vectors if Young's modulus, $E=210$GPa, Poisson's ratio, $v=0\mathrm{.}3,$ and density, $=0\mathrm{.}5k\frac{g}{m}3.$ Assume the element thickness $t=1m$ and the pressure P changes linearly from $0$ at node $1$ to $150$ Pa at node $3.$ Consider plane stress and plane strain cases.