Assertion: gauss's proof | /r/CapableOf | use the fact
Facets:
value: in order to reduce a geometric problem
type: PURPOSE
Source sentences:
text: In order to reduce a geometric problem to a problem of pure number theory, the proof uses the fact that a regular n-gon is constructible if and only if the cosine, cos ⁡ ( 2 π / n ) {\displaystyle \cos(2\pi /n)} , is a constructible number—that is, can be written in terms of the four basic arithmetic operations and the extraction of square roots.