I need help on this question: Triangle ABC is similar to triangle XYZ. What is the length of AC in inches?

Answer: 3√13
Step-by-step explanation:
To find the length of AC we need to use the Pythagorean theorem.
Which is AC^2 = BC^2 + AB^2
AC^2 = 6^2 + 9^2
AC^2 = 36 + 81
AC^2 = 117
AC = √117