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