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The area of the base of a cylinder is the area of a circle (in this case we define that the circle has a radius with measure ): B = π r 2 {\displaystyle B=\pi r^{2}} . To calculate the total area of a right circular cylinder, you simply add the lateral area to the area of the two bases:
For a given volume, the right circular cylinder with the smallest surface area has h = 2r. Equivalently, for a given surface area, the right circular cylinder with the largest volume has h = 2r, that is, the cylinder fits snugly in a cube of side length = altitude ( = diameter of base circle). [8]
Within the cylinder is the cone whose apex is at the center of one base of the cylinder and whose base is the other base of the cylinder. By the Pythagorean theorem , the plane located y {\displaystyle y} units above the "equator" intersects the sphere in a circle of radius r 2 − y 2 {\textstyle {\sqrt {r^{2}-y^{2}}}} and area π ( r 2 − y ...
The volume of the cone is 1/3 its base area times the height. The base of the cone is a circle of radius 2, with area , while the height is 2, so the area is /. Subtracting the volume of the cone from the volume of the cylinder gives the volume of the sphere:
The ratio of the volume of a sphere to the volume of its circumscribed cylinder is 2:3, as was determined by Archimedes. The principal formulae derived in On the Sphere and Cylinder are those mentioned above: the surface area of the sphere, the volume of the contained ball, and surface area and volume of the cylinder.
In speaking about these processes, the measure (length or area) of a figure's base is often referred to as its "base." By this usage, the area of a parallelogram or the volume of a prism or cylinder can be calculated by multiplying its "base" by its height; likewise, the areas of triangles and the volumes of cones and pyramids are fractions of ...
The magnitude of an object's solid angle in steradians is equal to the area of the segment of a unit sphere, centered at the apex, that the object covers.Giving the area of a segment of a unit sphere in steradians is analogous to giving the length of an arc of a unit circle in radians.
Proposition 2: The area of circles is proportional to the square of their diameters. [3] Proposition 5: The volumes of two tetrahedra of the same height are proportional to the areas of their triangular bases. [4] Proposition 10: The volume of a cone is a third of the volume of the corresponding cylinder which has the same base and height. [5]