Mathematical idealization of a crane has three bars with their vertices arranged as shown in the figure with a load of $80$ kN hanging vertically. The coordinates of the vertices are given in parentheses. The force in the member $QR$, $F_{QR}$ will be
1. $30$ kN Compressive
2. $30$ kN Tensile
3. $50$ Compressive
4. $50$ kN Tensile