180 ∘ = 2 ⋅ 2 ⋅ 5 ⋅ 3 ⋅ 3 1 ⋅ π 2 ⋅ 2 ⋅ 5 ⋅ 3 ⋅ 3 = π {\displaystyle {180^{\circ }}={\frac {{\cancel {2}}\cdot {\cancel {2}}\cdot {\cancel {5}}\cdot {\cancel {3}}\cdot {\cancel {3}}}{1}}\cdot {\frac {\pi }{{\cancel {2}}\cdot {\cancel {2}}\cdot {\cancel {5}}\cdot {\cancel {3}}\cdot {\cancel {3}}}}={\pi }}
