                                   CIRCLES                 HEP3.HLP

    The Circle program finds the center  of circles relative to other types
    of geometry.   In all  but the  first case  the radius  of the  unknown
    circle is given.  When you are prompted for the input you will be asked
    to enter a circle as X,Y,Radius or  a line as X,Y,Angle or X1,Y1,X2,Y2.
    The data  may be numeric values,  variables or expressions and  you may
    use the cursor keys, "Ins" and "Del" to edit your input.  The data must
    be separated by commas.  Press Enter only  after the one, two, three or
    four values have been entered separated by the commas.

    Example:
    Enter X,Y,Radius
       3.5, 7.125, 4  <Enter>    (Spaces are not required.)

    Case 1:  Find the circle that passes through three points.  You will be
    prompted for the input of the three points.  If the three points are on
    or near a straight line an Error message will be displayed.

    Case 2:   Find the  centers of  circles with  a given  radius that  are
    tangent to two  given circles or points.   The program will ask  you to
    enter the X,Y,Radius  for the first two  circles and the Radius  of the
    circles with the unknown center points.   Circles with a radius of zero
    are  considered points.   There can  be up  to eight  circles that  are
    possible  with the  given  input.  You  may be  asked  to indicate  the
    relationship between  a given circle and  the one to be  computed.  You
    must indicate  if the center  of a circle is  inside or outside  of the
    tangent  circle.   The X  and  Y  values  for  the tangent  points  are
    displayed.

    Case 3:  Find the  circles with a given radius that  are tangent to two
    defined lines.  The  program will ask for the definition  of two lines.
    These lines may be defined by giving two points, X1,Y1,X2,Y2, or by one
    point  and an  angle, X,Y,Angle.   The angle  is +/-  degrees from  the
    X-Axis with the Y-Axis at 90 degrees.  You will be asked for the radius
    of the circle.

    Case 4:  Find the  unknown values for a Segment and  Sector.  Enter the
    known values and for the unknown just press Enter.  (A sector is in the
    shape of a piece of pie.  A segment is  an area bounded by an arc and a
    straight line.)









