The planar structure $RST$ shown in the figure is roller-supported at $S$ and pin-supported at $R.$ Members $RS$ and $ST$ have uniform flexural rigidity $(EI)$ and $S$ is a rigid joint. Consider only bending deformation and neglect effects of self-weight and axial stiffening.
When the structure is subjected to a concentrated horizontal load $P$ at the end $T$, the magnitude of rotation at the support $R,$ is
- $\dfrac{PL^3}{12EI}$
- $\dfrac{PL^2}{12EI}$
- $\dfrac{PL^2}{6EI}$
- $\dfrac{PL}{6EI}$
