Number 10Please just show the math and not the sentence explanations, I just want to use this problem as an example :)

Explanation
We are given the following right-angled triangle:
We are required to determine the indicated angle in the given figure.
This is achieved thus:
According to the image, we have:
[tex]\begin{gathered} Opposite=9 \\ Adjacent=21 \end{gathered}[/tex]Therefore, we have:
[tex]\begin{gathered} \tan\theta=\frac{opposite}{adjacent} \\ \tan\theta=\frac{9}{21} \\ \theta=\tan^{-1}(\frac{9}{21}) \\ \theta\approx23\degree \end{gathered}[/tex]Hence, the answer is:
[tex]23\degree[/tex]