The area of the cross-section of a road fully in banking shown in the figure below is ____.
1
\(\frac{{{\rm{s}}{{\rm{b}}^2} + {{\rm{r}}^2}{{\left( {2{\rm{bd}} + {\rm{Sd}}} \right)}^2}}}{{{{\rm{r}}^2} - {{\rm{S}}^2}}}\)
2
\(\frac{{{\rm{S}}{{\rm{b}}^2} + {{\rm{r}}^2}{{\left( {2{\rm{bd}} - {\rm{Sd}}} \right)}^2}}}{{{{\rm{r}}^2} - {{\rm{S}}^5}}}\)
3
\(\frac{{{\rm{s}}{{\rm{b}}^2} + {{\rm{r}}^2}{{\left( {2{\rm{bd}} + {\rm{Sd}}} \right)}^2}}}{{{\rm{r}} - {\rm{s}}}}\)
4
\(\frac{{{\rm{S}}{{\rm{b}}^2} + {{\rm{r}}^2}{{\left( {2{\rm{bd}} - {\rm{Sd}}} \right)}^2}}}{{{\rm{r}} - {\rm{s}}}}\)