me assume yu meen a TRIANGEL........... yu sae a=x & c=x, so 2 sides the same... that make it a ISOSALEEZ triangel.... yu klaem us spozed tu yuze Pa-thag-a-ree-us... that impli yu thank it be a rite triangel..... If so, the other 2 angels gotta be 45 deg (both av em)... So the other side= root(2)*a...