Respuesta :

mathstudent55

Answer:

3.71

Step-by-step explanation:

AC² + BC² = AB²

3² + 6² = AB²

9 + 36 = AB²

AB = √45

AB = 3√5

AB = AD + BD

3√5 = 3 + BD

BD = 3√5 - 3

BD = 3.71