1. **State the problem:** We have a right triangle with two 45° angles, meaning it is an isosceles right triangle (45°-45°-90° triangle). One leg is given as $\sqrt{12}$, and we need to find the hypotenuse $x$. 2. **Recall the property of 45°-45°-90° triangles:** In such triangles, the legs are congruent, and the hypotenuse is $\sqrt{2}$ times the length of each leg. 3. **Write the formula:** $$x = \text{leg} \times \sqrt{2}$$ 4. **Substitute the known leg length:** $$x = \sqrt{12} \times \sqrt{2}$$ 5. **Simplify the expression:** $$x = \sqrt{12 \times 2} = \sqrt{24}$$ 6. **Simplify $\sqrt{24}$:** $$\sqrt{24} = \sqrt{4 \times 6} = \sqrt{4} \times \sqrt{6} = 2\sqrt{6}$$ 7. **Calculate the decimal approximation:** $$x \approx 2 \times 2.4495 = 4.899$$ 8. **Round to the nearest tenth:** $$x \approx 4.9$$ **Final answer:** $$\boxed{4.9}$$