#This program computes and displays the intersection points of a horizontal
#line with a circle centered at the origin.

import graphics as gph
import math as mth

def main():
    #User Instructions and Get Input
    print("This program computes and displays the intersection points")
    print("of a horizantal line at y = (a number) with a circle of radisu r")
    print("centered at the origin.\n")
    radius=float(input("Please input a radius for the circle:"))
    lineY=float(input("Input a Y value for the line:"))
    #Create GUI
    graph=gph.GraphWin("CircleGraph", 500,500)
    graph.setCoords(-10,-10,10,10)
    xAxis = gph.Line(gph.Point(-10,0), gph.Point(10,0))
    yAxis = gph.Line(gph.Point(0,-10), gph.Point(0,10))
    xAxis.setFill("blue")
    yAxis.setFill("blue")
    xAxis.setArrow("last")
    yAxis.setArrow("last")
    xAxis.draw(graph)
    yAxis.draw(graph)
    #cir=gph.Circle(gph.Point(0,0),radius)
    #cir.draw(graph)
    gph.Circle(gph.Point(0,0),radius).draw(graph)
    gph.Line(gph.Point(-10,lineY),gph.Point(10,lineY)).draw(graph)
    #Compute line-circle intersection points
    xIntercept1=mth.sqrt((radius**2)-(lineY**2))
    xIntercept2=xIntercept1*-1
    cirOne=gph.Circle(gph.Point(xIntercept1,lineY), 0.2)
    cirOne.setFill("red")
    cirOne.draw(graph)
    cirTwo=gph.Circle(gph.Point(xIntercept2,lineY), 0.2)
    cirTwo.setFill("red")
    cirTwo.draw(graph)




main()