title: Python3: Check if three sides provided able to form a triangle with nonzero area using triangle inequality
body: <p>I am given a question: To determine if the three positive float values (a,b,c) given by a user can represent the three side-lengths of a triangle with nonzero area; by using the triangle inequality theorem. No error checking is needed on the user input. </p>
  
  <p>The code below is the answer given on the answer sheet. However, I don't understand it, can someone kindly explain to me the purpose of 's' and 'eps' in the code? Thanks!</p>
  
  <pre><code>a = float (input ("Please enter a positive value, a: "))
  b = float (input ("Please enter a positive value, b: "))
  c = float (input ("Please enter a positive value, c: "))
  
  s = (a + b - c) * (a + c - b) * (c + b - a)
  
  eps = 0.0000001
  
  if abs(s) &gt; eps:
      print ("The 3 values form a triangle with non-zero area.")
  else:
      print ("The 3 values DO NOT form a triangle at all.")
  </code></pre>