Trademark paper area =785- 1× 10=775 cm2.

(4) Cylindrical wooden pier, bottom circumference 12.56dm, height 3dm, and calculated surface area.

Radius of bottom: 12.56÷3. 14÷2=2 (decimeter)

Bottom area: 3. 14×2? ×2=25. 12(dm？ )

Lateral area: 12.56×3=37.68(dm? )

Surface area: 25. 12+37.68=62.8 (square decimeter)

P9: (3) Each section is 0.6m long, so it is sawed into two sections.

The surface area is increased by two cross sections.

Bottom area:12.56/2 = 6.28cm2.

Volume: 6.28* 1.2=7.536 cubic centimeters.

(4) rotating around its length to obtain a cylinder with a bottom radius of 5cm and a height of 8cm, and the volume is:

3. 14× 5 2× 8 = 628 (cubic centimeter)

Rotating around its width, a cylinder with a bottom radius of 8 cm and a height of 5 cm is obtained. The volume is:

3. 14× 8 2× 5 = 1004.8 (cubic centimeter)

The volume rotating on a shaft with a large width is very large;

1004.8-628 = 376.8 (cubic centimeter)