A drainage system is designed to have equal base and edge length. $($a$)$ Develop a mathematical model for the cross$-$sectional area, $4,$ as a function of the base length, x$,$ and the edge elevation, B$.($b$)$ If the base length is fixed at $2$m$,$ determine the value of $8$ that maximizes the cross$-$sectional area of the drainage $($Assume the initial interval of uncertainty $[0,$ pi $/2]$ and precision, epsilon $=0\mathrm{.}05).$ Stop the solution after $3$ iterations.