$*6\mathrm{.}23$ Solve Laplace's equation for the two$-$dimensional electrostatic systems of Figure $6\mathrm{.}33$ and find the potential $\backslash ($ V$($x$,$ y$)\backslash ).($a$)$

$($b$)$

$($c$)$

FIGURE $6\mathrm{.}33$ For Problem $6\mathrm{.}23.$