6.1 Angles and Their Measure/41

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