3, 66 * 3.14 *100 = 20724 (cm) = 207.24m2000/207.24 is approximately equal to 10 (min).

4, (40*3. 14)/2=62.8 (cm)

40*3. 14*0.75=94.2 (cm)

5, 30*3. 14*3=282.6 (m)

(30*3. 14)/2 is approximately equal to 48 (root).

6、( 1) 16、 12.56

(2)9.42、2 1

7,25/2 =12.5 (cm)

8, 40 * 3.14 =125.6 (cm) =1.256 (m) 50/1.256 is approximately equal to 40 (circle).

9, 50*3. 14/2+50*4=278.5 (cm) =2.785 m.

10,10 * 3.14/2+5 * 3.14/2 * 2 = 31.4 (cm)

Hope to adopt