the answer:
ABC is a right triangle.
according to the figure, the length AC is the opposite side relative to the angle 40°,
for that, the main formula is
sin40° = opposite side / hypotenuse
opposite side =AC, and hypotenuse = 10 in
therefore, sin40° = AC / 10, and then AC = 10 sin40°
so for finding the value of AC, we can use AC = 10 sin40°
look at the image for more explanation
