title: Finding X and Y axis line intercept points of a Circle - Python
body: <p>Hey trying to learn how to code and I cant figure this exercise out.
  Specifically getting the precise y axis intercept points.
  The formula given works for getting the x axis points but I cant figure out how to get the y axis points.</p>
  
  <p>Exercise :</p>
  
  <p>Input : Radius of circle and the y - intercept of the line.</p>
  
  <p>Output : Circle drawn with a horizontal line across the window with the given y intercept. Mark two points of the intersection.
  Print the x values of the points of intersection *Formula : x = ± √r^2 - y^2 </p>
  
  <pre><code>Code::
  
      from graphics import *
      from math import *
  
      def main():
  
      # enter radius and the y intercept of the line
  
      radius = eval(input("Put in radius:: "))
      yinter = eval(input("Put in y intersec:: "))
  
      #Draw window + circle + line 
      win = GraphWin()
      win.setCoords(-10.0, -10.0, 10.0, 10.0)
      circle = Circle(Point(0.0,0.0), radius)
      mcircle = Circle(Point(0.0,0.0), 0.5)
      circle.draw(win)
      mcircle.draw(win)
  
      line = Line(Point(-10, 0), Point(10, yinter))
      line.draw(win)
  
      #Calculate x axis points of intersept  
      xroot1 = sqrt(radius * radius - yinter * yinter)
      xroot2 = -abs(xroot1)
      print("Xroot 1 : ", xroot1)
      print("Xroot 2 : ", xroot2)
  
      x = 0
      yroot1 = sqrt(radius * radius - x * x)
      yroot2 = -abs(yroot1)
      print("Yroot 1 : ", yroot1)
      print("Yroot 2 : ", yroot2)
  
      #mark two points of intersept in red 
      sc1 = Circle(Point(xroot1, yroot1), 0.3)
      sc1.setFill('red')
      sc2 = Circle(Point(xroot2, yroot2), 0.3)
      sc2.setFill('red')
      sc1.draw(win)
      sc2.draw(win)
  
      main()
  
  Answer - With Radius of 8 and Y intersect point of 2
  Yroot1 = 7.75
  Yroot2 = -7.75
  Xroot1 = 8.0
  Xroot2 = -8.0
  </code></pre>