Some properties of a regular heptagon

Show that [math]GC\ne\sqrt{5}[/math], [math]BH\ne\frac{\sqrt{3}}{2}[/math], but [math]EH=\sqrt{2}[/math]. (Hint: Type [code]Relation(EH^2,2AB^2)[/code].)

Information: Some properties of a regular heptagon