Prove that `cos^(-1).(4).(5) + cos^(-1).(12)/(13) = cos^(-1).(33)/(65)`

Explanation

To prove that \( \cos^{-1}\left(\frac{4}{5}\right) + \cos^{-1}\left(\frac{12}{13}\right) = \cos^{-1}\left(\frac{33}{65}\right) \), we will follow these steps:

### Step 1: Define the angles
Let:
\[ x = \cos^{-1}\left(\frac{4}{5}\right) \]
\[
...