B
71) As we have a right triangle, one leg and another missing then we can use a trigonometric ratio to find that out.
Note that the missing leg is the hypotenuse (opposite to the right angle):
[tex]\begin{gathered} \sin (64^{\circ})=\frac{\text{opposite side}}{hypotenuse} \\ \sin (64^{\circ})=\frac{45}{x} \\ \sin (64^{\circ})x\text{ =45} \\ \frac{\sin (64^{\circ})x}{\sin (64^{\circ})}=\frac{45}{\sin (64^{\circ})} \\ x\approx50 \end{gathered}[/tex]
2) Note that we've crossed multiplied and then divided both sides by the same quantity sin(64)
3) Hence, the missing side (hypotenuse) is approximately 50 ft
