title: How to calculate angle between 3 polar coordinate points?
body: <pre><code>FY00 = [0, 0]
  
  FY01 = [100, 0]
  
  FY02 = [98, 40.10]
  </code></pre>
  <p>I have 3 points like this, first param is ρ, second param is θ, I want calculate ∠FY00-FY01-FY02 using python, how to do that?</p>