Figure uses three dashed arcs and one small circle. Dashed line or arc is a style attribute that can be attached with a line or a curve. In OpenGL you can use the line stipple functions to produce such output. Use the midpoint circle algorithm to get the output of your program as in Figure. 

E6)   Again this is a concentric circular arc drawing problem.  Draw a circle first with smallest radius and then for the remaining three circles plot only the pixels (x_c+ x, y_c+y) until y =x . Implement dashed arcs as done in the solution to E3).  Modify your circle drawing code circleMidpoint()accordingly.