Groups and FieldsHardSplitting Fields and Constructions ShareSplitting Fields and Constructions · Hard problemWhat is the degree over Q\mathbb QQ of cos2π9\cos\frac{2\pi}9cos92π, and is the regular 999-gon constructible?ADegree 333; not constructibleBDegree 222; constructibleCDegree 666; not constructibleDDegree 333; constructibleCheck Show answer Walk through it step by step Practice more like this Review this concept