Por propriedade:
[tex3]\mathsf{6\theta = 120-2\theta\implies \theta=15^o\\
\therefore BD=l_{12}\\(a_c=\frac{360^o}{n}\rightarrow 30^o =\frac{360}{n}\therefore n =12)\\
\triangle BCD(isósceles)\implies BD = R.\sqrt{2-\sqrt3}\implies\\
BD = \sqrt{2+\sqrt3}\cdot\sqrt{2-\sqrt3} \\
\therefore \boxed{\color{red}BD = \sqrt1 = 1}
}[/tex3]...