1. The problem involves a right-angled triangle with an angle of 64° and sides labeled 5.8 m and u. 2. We need to determine which equation is correct: A) $\sin 64^\circ = \frac{5.8}{u}$ or B) $\sin 64^\circ = \frac{u}{5.8}$. 3. Recall that $\sin \theta = \frac{\text{opposite side}}{\text{hypotenuse}}$. 4. Here, the side opposite the 64° angle is $u$, and the hypotenuse is 5.8 m. 5. Therefore, the correct equation is B: $\sin 64^\circ = \frac{u}{5.8}$. 6. To find $u$, rearrange equation B: $$u = 5.8 \times \sin 64^\circ$$ 7. Calculate $\sin 64^\circ$: $$\sin 64^\circ \approx 0.8988$$ 8. Multiply: $$u = 5.8 \times 0.8988 = 5.213$$ 9. Round to 1 decimal place: $$u \approx 5.2$$ Final answer: $u = 5.2$ m