What is the value of $\sin\left(\sin^{-1} \frac{2}{7} + \cos^{-1} \frac{2}{7}\right)$?

Explanation

1. 01

   $\sin^{-1} \frac{2}{7} + \cos^{-1} \frac{2}{7} = \frac{\pi}{2}$, because $\frac{2}{7}$ is in $[-1, 1]$.

2. 02

   $\sin \frac{\pi}{2} = 1$.