There is a fixed line and a moving line in the same plane. When a plane rotates once around a fixed line, the surface formed by the moving line is called the rotating surface, the fixed line is called the axis of the rotating surface, and the moving line is called the generatrix of the rotating surface.
The side surface of the cylinder is a curved surface, and the development diagram of the side surface of the cylinder is a rectangle, a square or a parallelogram (diagonal cutting).
Transverse area of cylinder = X height of bottom circumference, i.e.:
S transverse area =Ch=2πrh.
Bottom circumference C=2πr=πd
Surface area of cylinder = lateral area+bottom area x2 = ch+2π r 2 = 2π r (r+h).
Extended data:
There is a fixed line and a moving line in the same plane. When a plane rotates once around a fixed line, the surface formed by the moving line is called the rotating surface, the fixed line is called the axis of the rotating surface, and the moving line is called the generatrix of the rotating surface. If the bus is a straight line parallel to the axis.
The bottom of a cylinder is two completely equal circles, and only one of the bottom of a cone is a circle.
The distance between the two bottom surfaces is called the height of the cylinder. A cylinder has countless heights, all of which are of equal length. The distance from the apex of the cone to the center of the bottom surface is called the height of the cone, and the cone has only one height.
The sides of cylinders and cones are curved surfaces. However, the lateral expansion of a cylinder is square or rectangular (along high shear), while the lateral expansion of a cone is fan-shaped.
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