6.1 Angles and Their Measure/43

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