Click the thumbnails to enlarge.

Sum of circles (Figure 4.3.1)

Getting sphere (Figure 4.3.2 and 4.3.3)

Example 5 (Figures 4.3.4 and 4.3.5)

Example 6 (Figures 4.3.6 and 4.3.7)

A sphere from a disc (Figure 4.3.8)

Sphere from disk; alternative (Figure 4.3.9)