$-4\mathrm{.}80$ In the preceding problem, illustrate on a graph of

$W_c$ versus $d$ the safe region of points $(d,W_c)$ for which both

conditions $($a$)$ and $($b$)$ will be satisfied. Consider only

values of $d>2ft$ for practical reasons$\mathrm{.}4\mathrm{.}80$ In the preceding problem, illustrate on a graph of

$W_c$ versus $d$ the safe region of points $(d,W_c)$ for which both

conditions $($a$)$ and $($b$)$ will be satisfied. Consider only

values of $d>2ft$ for practical reasons.