1. **State the problem:** We have a right triangle with one angle of 36°, the side opposite this angle is 12, and the adjacent side to this angle is $x$. We need to find the length of side $x$. 2. **Formula used:** In a right triangle, the tangent of an angle is the ratio of the opposite side to the adjacent side: $$\tan(\theta) = \frac{\text{opposite}}{\text{adjacent}}$$ 3. **Apply the formula:** Here, $\theta = 36^\circ$, opposite side = 12, adjacent side = $x$. $$\tan(36^\circ) = \frac{12}{x}$$ 4. **Solve for $x$:** Multiply both sides by $x$: $$x \tan(36^\circ) = 12$$ Divide both sides by $\tan(36^\circ)$: $$x = \frac{12}{\tan(36^\circ)}$$ 5. **Calculate the value:** Using a calculator, $$\tan(36^\circ) \approx 0.7265$$ So, $$x = \frac{12}{0.7265} \approx 16.52$$ **Final answer:** $$x \approx 16.52$$