Answer
$${135^ \circ }$$
Work Step by Step
$$\eqalign{
& \frac{{3\pi }}{4} \cr
& {\text{we know that 1 radian}} = \left( {\frac{{{{180}^ \circ }}}{\pi }} \right){\text{. }}\left( {{\text{see}}\,\,{\text{page 668}}} \right){\text{ Then}}{\text{,}} \cr
& \frac{{3\pi }}{4}{\text{radians}} = \frac{{3\pi }}{4}\left( {\frac{{{{180}^ \circ }}}{\pi }} \right) \cr
& {\text{multiplying}} \cr
& \frac{{3\pi }}{4}{\text{radians}} = \frac{{3\left( {{{180}^ \circ }} \right)}}{4} \cr
& \frac{{3\pi }}{4}{\text{radians}} = 3\left( {{{45}^ \circ }} \right) \cr
& \frac{{3\pi }}{4}{\text{radians}} = {135^ \circ } \cr} $$