x = A 21.6 B 12.9 C 9.1

Answer:
B: 12.9
Step-by-step explanation:
If A B and C are the alternatives, the answer is B: 12.9
The reason is that the hypotenuse can't be smaller than one of its sides, that eliminates alternative C.
And also, the hypotenuse can't be bigger than segments AC + BC, since the side AC is bigger and AC measures 10.8, the hypotenuse would have to measure < 21.6
Any questions, comment.
Answer:
B
Step-by-step explanation:
Using the sine ratio in the right triangle
sin57° = [tex]\frac{opposite}{hypotenuse}[/tex] = [tex]\frac{AC}{AB}[/tex] = [tex]\frac{12}{x}[/tex] ( multiply both sides by x )
x × sin57° = 12 ( divide both sides by sin57° )
x = [tex]\frac{12}{sin57}[/tex] ≈ 12.9 ( to 1 dec. place ) → B