Can you please explain the correct answer

 For this case we have as data:
 1) hypotenuse of the triangle
 2) Angle between the base of the triangle and the hypotenuse.
 Therefore, we can use the following trigonometric relationship:
 [tex]sine (40) = AC / 10 [/tex]
 From here, we clear the value of AC.
 We have then:
 [tex]AC = 10 * sine (40) [/tex]
 Answer:
 The encuacion that can be used to find the length of AC is given by:
 [tex]AC = 10 * sine (40) [/tex]
 option 1