120 ∘ ⋅ π 180 ∘ = 2 ⋅ 2 ⋅ 2 ⋅ 3 ⋅ 5 1 ⋅ π 2 ⋅ 2 ⋅ 5 ⋅ 3 ⋅ 3 = 2 π 3 {\displaystyle 120^{\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 {2\pi }{3}}}
