How many cm2 is the surface area increased by sawing a 2 cm long cylindrical wood with a bottom radius of 10 cm into six identical cylindrical pieces?

How many cm2 is the surface area increased by sawing a 2 cm long cylindrical wood with a bottom radius of 10 cm into six identical cylindrical pieces?

10×10×3.14×(6×2－2)
＝314×10
＝3140
A: the surface area has increased by 3140cm

If a 4-meter-long cylindrical wood with a bottom radius of 20 cm is sawed into three cylindrical wood of the same length, how many square meters will the surface area increase?

Four sections are added, (3.14 * 0.2 * 0.2) * 4 = 0.5024 (M2)

The height of the tree is 10 meters and the diameter is 1.8 meters. How many cubic meters are there?

Tree volume = π (R ^ 2) H = 3.14 × 0.9 × 0.9 × 10 = 25.434 (M3)