Formelsammlung

Achteck

Inkreisradius

$r_{i}=a\ {\frac {1}{2}}(1+{\sqrt {2}})$

$a=2r_{i}\ ({\sqrt {2}}-1)$

Umkreisradius

$r_{u}=a\ {\frac {1}{2}}{\sqrt {4+2{\sqrt {2}}}}$

$r_{u}=a\ {\sqrt {1+{\frac {1}{\sqrt {2}}}}}$

$a=r_{u}\ {\sqrt {2-{\sqrt {2}}}}$