Plz help here

Step 1: Identify the type of triangle and the known sides. The given triangle ABC is a right-angled triangle, with the right angle at B. The sides AB and BC are the legs, and AC is the hypotenuse.

Step 2: State the Pythagorean theorem. For a right-angled triangle, the square of the hypotenuse ($c$) is equal to the sum of the squares of the other two sides ($a$ and $b$). $a^2 + b^2 = c^2$

Step 3: Substitute the given values into the theorem. Here, $a = AB = 12$ cm and $b = BC = 5$ cm. We need to find $c = AC$. $(12 cm)^2 + (5 cm)^2 = AC^2$

Step 4: Calculate the squares of the known sides. $144 cm^2 + 25 cm^2 = AC^2$

Step 5: Add the squared values. $169 cm^2 = AC^2$

Step 6: Take the square root of both sides to find the length of AC. $AC = \sqrt{169 cm^2}$

Step 7: Calculate the square root. $AC = 13 cm$

The length of side AC is $\boxed{13 cm}$.