s=？ r2

=3. 14* 16

= 12.56

r=2+ 1=3

s=？ r2

=3. 14*9

=28.26

28.26- 12.56= 15.7

7. Solve the circle with s=s length+s.

=80*60+? r2

= 4800+900?

=4800*3. 14

=7626 (yuan)

7626*42=320292 yuan

8. Solution P = 16=8.

r=4

S yin = square of pair-square of 2pair.

= Row 64-Row 32

= 32 pai

=32*3. 14

Approximately equal to 100.5.

C=2pai r squared +2pai r*2

= 2pai*8+2pai*4*2

= 16 school+16 school

= 32 pai

=32*3. 14

Approximately equal to 100.5.