SOLUTION
This is a right-angled triangle problem, and to solve for an unknown side, we will apply the Pythagoras theorem.
Pythagoras theorem states:

From the question:
Hypotenuse = 13in
Opposite = 5in
Adjacent = b
Substituting all these paramenters into the equation above:

![\begin{gathered} 169-25=b^2 \\ 144=b^2 \\ \text{Take the square root of both sides} \\ \sqrt[]{144\text{ }}=\text{ }\sqrt[]{b^2} \\ 12=b \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/2qj83pxwk4nb6fejonaoi5pg7nv6k3n341.png)
The value of b is 12 in