Draw a big arc first: draw a rectangle ABCD, width 100, height 60, and connect diagonal AC to make it the middle vertical line of AC. Draw a circle with E as the center and AE as the radius against the extension line of AD, and cut out the AC arc, which is the required big arc.

Continue to draw the picture on the right: offset AE line by 130 to get straight line FG. The diagram to be drawn is as shown below, with two concentric circles (called a big circle and a small circle with the center of O), and all the known parameters have been added to the diagram. Let the radius of the small circle be r, then in the right angle △CHO, there is a relationship of side length: co 2 = ch 2+ho 2. CO=20+r, CH=60-20-r and HO=30. Substituting them into this equation, the result is r= 17.5. So the radius of the great circle is 20+r = 37.5. Accordingly, the AC arc moves outward by 37.5, intersects with the straight line FG at point O, draws a small circle with a radius of 17.5, draws a big circle with a radius of 37.5, connects AF, and cuts the big circle with FC as the boundary, leaving a larger arc part. Finally, fill the small circle with the h command. Finish painting.