Answer:
6.7 ft
Step-by-step explanation:
Use pythagorean theorem:
[tex] {a}^{2} + {b}^{2} = {c}^{2} [/tex]
where c is the hypotenuse of the triangle
[tex] {a}^{2} + {6}^{2} = {9}^{2} [/tex]
[tex] {a}^{2} + 36 = 81[/tex]
[tex] {a}^{2} = 45[/tex]
[tex]a = \sqrt{45} [/tex]
[tex]a = 6.7[/tex]
