6.1 Angles and Their Measure/43

$-135^{\circ }\cdot {\frac {\pi }{180^{\circ }}}={\frac {{\cancel {3}}\cdot -3\cdot {\cancel {3}}\cdot {\cancel {5}}}{1}}\cdot {\frac {\pi }{{2}\cdot {2}\cdot {\cancel {5}}\cdot {\cancel {3}}\cdot {\cancel {3}}}}=-{\frac {3\pi }{4}}$