title: determine whether point lies inside triangle
body: <p>The program needs to read the values of three coordinates   </p>
  
  <ul>
  <li>P1(x1,y1)</li>
  <li>P2(x2,y2)</li>
  <li>P3(x3,y3) </li>
  </ul>
  
  <p>as well as another coordinate P(x,y) and determine whether this point is inside a triangle formed from the 3 point above.</p>