1. **State the problem:** Calculate the length of the diagonal path of a rectangular area with length 18m and width 12m, expressing the answer in surd form. 2. **Recall the formula:** The diagonal $d$ of a rectangle with length $l$ and width $w$ is given by the Pythagorean theorem: $$d = \sqrt{l^2 + w^2}$$ 3. **Substitute the given values:** $$d = \sqrt{18^2 + 12^2}$$ 4. **Calculate the squares:** $$d = \sqrt{324 + 144}$$ 5. **Add the values inside the square root:** $$d = \sqrt{468}$$ 6. **Simplify the surd:** Find the largest perfect square factor of 468. Since $468 = 36 \times 13$, we have: $$d = \sqrt{36 \times 13} = \sqrt{36} \times \sqrt{13} = 6\sqrt{13}$$ 7. **Final answer:** The length of the diagonal path is $6\sqrt{13}$ meters in surd form.