The instructions used in the first example should be used.

Just use the name arc_circle.py when you write, save and execute this program.

# arc_circle.py
#>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>              
from Tkinter import *
root = Tk()
root.title('Should be a circle')
cw = 210                                      # canvas width
ch = 130                                      # canvas height
canvas_1 = Canvas(root, width=cw, height=ch, background="white")
canvas_1.grid(row=0, column=1)                              

xy = 20, 20, 320, 320         # bounding box from x0,y0 to x1, y1
 # The Arc is drawn  from start_angle, in degrees to finish_angle.
# but if you try to complete the circle at 360 degrees it evaporates.
canvas_1.create_arc(xy, start=0, extent=359.999999999, fill="cyan")
root.mainloop()
#>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

The results are given in the next screenshot, showing a failed circle resulting from create_arc().

Generally the create_arc() method is not the best method of making complete circles because an attempt to go from 0 to 360 degrees results in the disappearance of the circle from view. Rather use the create_oval() method. However, there are occasions when you need the properties of the create_arc() method to be able to create a particular distribution of color. See the color wheel in the later chapters for a good example of this.

The create_arc() method is well suited to the production of the pie charts favored in corporate presentations. The create_arc() method draws a segment of a circle with the ends of the arc joined to the center by radial lines. But if we just want to draw a circle those radial lines are unwanted.