cos π 6 = 3 2 {\displaystyle \cos {\frac {\pi }{6}}={\frac {\sqrt {3}}{2}}}
cos π 4 = 2 2 {\displaystyle \cos {\frac {\pi }{4}}={\frac {\sqrt {2}}{2}}}
cos π 3 = 1 2 {\displaystyle \cos {\frac {\pi }{3}}={\frac {1}{2}}}