使用畢氏定理會發現 PD = (PA**2+PC**2-PB**2)**0.5
程式碼自己看
try :
  while True:
    pa,pb,pc = map(int, input().split())
    pd = (pa * pa + pc * pc - pb * pb) ** 0.5
    print('%0.2f' % (pd))	
except EOFError:
    pass