"I figured it out!" (3)
(Other definitions for eureka that I've seen before include "I've got it!" , "Archimedes's cry of discovery" , "discovery that's brilliant" , "Shriek of discovery" , "Greek cry of discovery by Archimedes" .)
(Other definitions for aha that I've seen before include "Cry of triumph" , "I've got it!" , "Palindromic exclamation of triumph or surprise" , "Surprised expression" , "Exclamation of triumph or mockery, a palindrome" .)