Answer:
Option A. [tex]7.2\ units[/tex]
Step-by-step explanation:
see the attached figure to better understand the problem
we know that
In the right triangle ACD
[tex]cos(A)=\frac{AD}{AC}=\frac{5}{6}[/tex] ------> equation A
In the right triangle ABC
[tex]cos(A)=\frac{AC}{AB}=\frac{6}{AB}[/tex] ------> equation B
equate equation A and equation B and solve for AB
[tex]\frac{5}{6}=\frac{6}{AB}[/tex]
[tex]AB=6*6/5=7.2\ units[/tex]
