Drawing by Polar Coordinates 
-  Some figures are easier to be represented by 
polar
coordinates
than Cartesian
coordinates.
 -  Consider the figure of the function 
r = sin ( 5 * theta )
 
 -  You may convert 
the polar coordinate (r,theta) 
to
the Cartesian coordinate (x,y) 
    by
    
    -  x = r * cos (theta)
    
 -  y = r * sin (theta)