Respuesta :

Roughly 11. :') Tell me if you need me to explain how I got that number, I'll gladly elaborate. 
DC² = 5² - 3²       By Pythagoras' Theorem

DC² = 25 -9 =16

DC = √16 = 4

AC = AD + DC = AD + CD = 7 + 4 = 11

AB² = BC² + AC²

AB² = 3² + 11² = 9 + 121 = 130

AB² = 130

AB = √130

AB ≈ 11.402