Answer:
[tex]AC=\sqrt{130}[/tex]
Step-by-step explanation:
AC is the geometric mean. Solve it using this proportion:
[tex]\frac{BC}{AC}=\frac{AC}{CD}[/tex]
Now fill in the values we know:
[tex]\frac{5}{AC}=\frac{AC}{26}[/tex]
Cross multiply to get
[tex](AC)^2=130[/tex]
That means that
AC = [tex]\sqrt{130}[/tex], which, in decimal form is
AC = 11.40175425
