Answer:
C
Step-by-step explanation:
Since ΔABC is right use the sine ratio to find AB
sin30° = [tex]\frac{opposite}{hypotenuse}[/tex] = [tex]\frac{AC}{AB}[/tex], hence
sin30° = [tex]\frac{10}{AB}[/tex] ( cross- multiply )
AB × sin30° = 10 ( divide both sides by sin30° )
AB = [tex]\frac{10}{sin30}[/tex] = 20 ft → C
