#### Answer

$\sin(A)=\frac{4}{5}$

#### Work Step by Step

The sine of an angle in a right triangle is the ratio of the opposite side to the hypotenuse. The side opposite $A$ has a measure of $8$, and the hypotenuse has a measure of $10$. When we write these in a ratio, we get $\frac{8}{10}$, which simplifies to $\frac{4}{5}$.