Question 528·Medium·Math

No Desmos needed. The figure gives both sides for sine, and their fraction reduces by one division. The right-angle marker is at $R$, so the slanted ramp $PQ=26$ is the hypotenuse, the side across from the right angle. From $A$ at $P$, the vertical rise $RQ=10$ is the opposite side because it sits across from $P$.

Sine means opposite divided by hypotenuse. Use the vertical rise over the slanted ramp: $\sin A=\frac{10}{26}$. The horizontal run is next to $A$, so rise over run would give tangent instead.

Both $10$ and $26$ are divisible by $2$, so divide the top and bottom by $2$: $\sin A=\frac{10\div2}{26\div2}$. Evaluate those divisions: $\sin A=\frac{5}{13}$. So the sine of the angle between the ramp and ground is $\frac{5}{13}$. Choice A.