▁edge ▁lengths ▁multip lied ▁by ▁the ▁exterior ▁di hed ral ▁angles . ▁Thus ▁( for ▁poly hed ra ▁without ▁rational ▁angles ) ▁it ▁is ▁a ▁linear ▁function ▁of ▁the ▁De hn ▁invariant , ▁although ▁it ▁does ▁not ▁provide ▁full ▁information ▁about ▁the ▁De hn ▁invariant . ▁It ▁has ▁been ▁proven ▁to ▁remain ▁constant ▁for ▁any ▁flex ing ▁poly hed ron . ▁ ▁References ▁ ▁External ▁links ▁▁ ▁Video ▁about ▁De hn ▁invari ants ▁on ▁Number ph ile ▁ ▁Category : Ge ometric ▁dis section ▁Category : Pol y hed ra <0x0A> </s> ▁Kath arina ▁D üll ▁( born ▁ 9 ▁April ▁ 1 9 7 3 ) ▁is ▁a ▁German ▁former ▁professional ▁tennis ▁player . ▁ ▁D üll ▁was ▁a ▁member ▁of ▁West ▁Germany ' s ▁World ▁Youth ▁Cup ▁( J un ior ▁Fed ▁Cup ) ▁winning ▁team ▁in ▁ 1 9 8 9 . ▁On ▁the ▁professional ▁tour , ▁she ▁reached ▁a ▁career ▁high ▁singles ▁ranking ▁of ▁ 2 2 5 ▁in ▁the ▁world . ▁She ▁made ▁the ▁second ▁round ▁of ▁the ▁ 1 9 8 7 ▁Argent ine ▁Open ▁in ▁Buenos ▁Aires ▁and ▁ 1 9 8 9 ▁Cit izen ▁Cup ▁in ▁Hamburg . ▁ ▁References ▁ ▁External ▁links ▁▁▁▁▁ ▁Category : 1 9 7 3 ▁birth s ▁Category : L iving ▁people ▁Category : West ▁German ▁female ▁tennis ▁players ▁Category : G erman ▁female ▁tennis ▁players <0x0A> </s> ▁Home ▁is ▁a ▁live ▁album ▁by ▁American ▁metal core ▁band ▁August ▁Burn s ▁Red ▁released ▁through ▁Sol id ▁State ▁Records . ▁in