What's the bottom area of this cylinder? How many are the bottom areas? Two bottom areas or one? What is the bottom area of a cylinder with a side length of 12.56 decimeters?

It's one I'm sure. Please take it
Because the volume of the cylinder is the height of the bottom area
The teacher said that

How to calculate the area of a circle with a diameter of 6 meters and a cylinder with a diameter of 1.5 meters and a height of 2 meters?

The area of a circle is: the circumference times the square of the radius
The diameter is 6m and the radius is 3M
So the area is: π * 3 * 3 = 3.14 * 3 * 3 = 28.26 (M2)
The side area of the cylinder is: base perimeter times height, base perimeter equals circumference times diameter
The area of the bottom of the cylinder is: the circumference times the square of the radius of the bottom
The surface area of the cylinder is: 2 times the bottom area plus the side area
So the side area of the cylinder is: (π * 1.5) * 2 = 9.42 (M2)
Zhou Changgao
The area of cylinder bottom is: π * 0.75 * 0.75 = 1.76625 (M2)
Bottom radius
Cylinder surface area: 9.42 + 2 * 1.76625 = 12.9525 (M2)

How to calculate the area of a cylinder with a diameter of 5 mm and a length of 250 mm

Area = perimeter × height
S = D × H
=3.14×5×250
=3925 sq mm

The diameter of the bottom surface of a cylinder is twice the height, and its side area is 60 square centimeters. Find the surface area of the cylinder

Let the height of the cylinder be h, then the diameter of the bottom is 2h, and the radius r = H,
S side = 2 π RH = 2 π h * H = 2 π H ^ 2 = 60
S table = 2 * π * r * H + 2 π * r * r
=2πh^2+2πh^2
=60 + 60 = 120 square centimeter

What's the bottom area of this cylinder? How many are the bottom areas? Two bottom areas or one? What is the bottom area of a cylinder with a side length of 12.56 decimeters?