Surface area: 1. Bottom radius 3cm, height 5cm. 2. Bottom perimeter 15.7cm, height 4cm. 3. Bottom diameter 4cm, height 4cm 4. Lateral area 62.8dm, height 5DM

Surface area: 1. Bottom radius 3cm, height 5cm. 2. Bottom perimeter 15.7cm, height 4cm. 3. Bottom diameter 4cm, height 4cm 4. Lateral area 62.8dm, height 5DM

Qianshitong 2:
（1）3cm×2×3.14×5cm+（3cm）²×3.14×2＝94.2cm²+56.52cm²＝150.72cm²
（2）15.7cm×4cm+（15.7cm÷3.14÷2）²×3.14×2＝62.8cm²+39.25cm²＝102.05cm²
（3）4cm×3.14×4cm+（4cm÷2）²×3.14×2＝50.24cm²+25.12cm²＝75.36cm²
（4）62.8dm²+（62.8dm²÷5dm÷3.14÷2）²×3.14×2
＝62.8cm²+4dm²×3.14×2＝62.8dm²+25.12dm²＝87.92dm²
Good luck and goodbye

The circumference of the bottom surface of a half cylinder is 20.56, and the height is 5cm

The bottom radius is 20.56 △ 3.14 + 2 = 4cm
The surface area of this half cylinder is:
3.14×4×4+3.14×2×2×5+2×2×5
=50.24+62.8+20
=133.04 square cm

The bottom radius of a cylinder is 0.5cm. What is the 5cm surface area?

Floor area
0.5 × 0.5 × 3.14 = 0.875 (cm2)
Lateral area
0.5 × 2 × 3.14 × 3.5 = 10.99 (cm2)
Surface area
875 × 2 + 10.99 = 12.56 (cm2)

The diameter of the bottom surface is 6cm, the height is 12cm, and the surface area is calculated

Bottom radius = 6 / 2 = 3cm
Bottom area = 3 * 3 * 3.14 = 28.26 square centimeter
Side area = 6 * 3.14 * 12 = 226.08 square centimeter
Surface area = 28.26 * 2 + 226.08 = 282.6 square centimeter