1, the bottom of the cylinder is round and the size is the same.

2. The distance between two sides of a cylinder is called height. Open the side of the cylinder and get a rectangle. The length of this rectangle is the circumference of the bottom of the cylinder.

There are countless heights and symmetry axes.

Lateral area of the extended data cylinder = the height of the bottom perimeter of X, that is, S lateral area =Ch=2πrh.

(bottom circumference C=2πr=πd)

Surface area of cylinder = lateral area+bottom area x2=Ch+2πr*2=2πr(r+h).

Volume of cylinder = bottom area x height, that is, V=S bottom area x h = (π× r× r) h.

References:

Baidu encyclopedia-cylinder