Answer: Option B.
Step-by-step explanation:
You neeed to use the trigonometric identity:
[tex]sin\alpha=\frac{opposite}{hypotenuse}[/tex]
As you need to find sin∠A, you can identify in the right triangle that:
[tex]opposite=8\\hypotenuse=10\\\alpha=A[/tex]
Finally, substitute the angle, the lenght of the opposite side and the lenght of the hypotenuse into [tex]sin\alpha=\frac{opposite}{hypotenuse}[/tex] to find sin∠A. Then, you get:
[tex]sinA=\frac{8}{10}[/tex]
Reducing the fraction:
[tex]sinA=\frac{4}{5}[/tex]
This is the option B.
