30 ∘ ⋅ π 180 ∘ = 2 ⋅ 3 ⋅ 5 1 ⋅ π 2 ⋅ 2 ⋅ 5 ⋅ 3 ⋅ 3 = π 6 {\displaystyle 30^{\circ }\cdot {\frac {\pi }{180^{\circ }}}={\frac {{\cancel {2}}\cdot {\cancel {3}}\cdot {\cancel {5}}}{1}}\cdot {\frac {\pi }{{\cancel {2}}\cdot {2}\cdot {\cancel {5}}\cdot {\cancel {3}}\cdot 3}}={\frac {\pi }{6}}}
− 5 π 4 ⋅ 1 = − 5 π 4 ⋅ 180 π = − 225 ∘ {\displaystyle {\frac {-5\pi }{4}}\cdot {1}={\frac {-5\pi }{4}}\cdot {\frac {180}{\pi }}=-225^{\circ }}
