Answer
$${100^ \circ }$$
Work Step by Step
$$\eqalign{
& \frac{{5\pi }}{9}{\text{radians}} \cr
& {\text{We know that 1 radian}} = \left( {\frac{{{{180}^ \circ }}}{\pi }} \right){\text{. }}\left( {{\text{see}}\,\,{\text{page 668}}} \right){\text{ Then}}{\text{,}} \cr
& \frac{{5\pi }}{9}{\text{radians}} = \frac{{5\pi }}{9}\left( {\frac{{{{180}^ \circ }}}{\pi }} \right) \cr
& {\text{multiplying}} \cr
& \frac{{5\pi }}{9}{\text{radians}} = \frac{{5\left( {{{180}^ \circ }} \right)}}{9} \cr
& \frac{{5\pi }}{9}{\text{radians}} = \frac{{{{900}^ \circ }}}{9} \cr
& \frac{{5\pi }}{9}{\text{radians}} = {100^ \circ } \cr} $$
