Respuesta :

gmany
The formula of the area of a triangle:

[tex]A_\Delta=\dfrac{bh}{2}[/tex]

b - a base
h - a height

We have:
h = 6ft.and A=9 ft.²

substitute:

[tex]\dfrac{6b}{2}=9\\\\3b=9\ \ \ |:3\\\\b=3\ ft.[/tex]

Answer: b = 3ft.