title: Intersection or Solve
body: <p>Consider the Following :</p>
  
  <pre><code>daList = {{541, 0.0593368}, {550, 0.298352}, {560, 0.72619}, {570,0.734982}, 
            {580, 1.46149}, {590, 2.31119}, {600, 3.31509}}
  </code></pre>
  
  <p>Each sublist represent an {x,y} coordinate.</p>
  
  <p>I need to find the x value for which the Y is equal to 1. Roughly 575 with the eye.</p>
  
  <pre><code>ListPlot[daList, 
          Joined -&gt; True, 
          Epilog -&gt;{Thick, Line[{{0, 1}, {600, 1}}]}]
  </code></pre>
  
  <p>+Help from PPT  for the Red parts to illustrate the question :</p>
  
  <p><img src="https://i.stack.imgur.com/0yzOY.png" alt="enter image description here"></p>
  
  <p>Could interpolate till I find 1 but I want to know if there exist a function for this in Mathematica.</p>
  
  <p>Either a computation. Find the X for which y = 1.
  Or maybe a graphical one in which line intersection x coordinate is reported on the x-axis.</p>