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≡ 0.3048 m ≡ 1 ⁄ 3 yd ≡ 12 inches ≡ 0.3048 m foot (Sear's) (H) ... the center of a sphere of radius r by a portion of the sphere having an area r 2. A ...
Thus, the segment volume equals the sum of three volumes: two right circular cylinders one of radius a and the second of radius b (both of height /) and a sphere of radius /. The curved surface area of the spherical zone—which excludes the top and bottom bases—is given by =.
In mathematics, a unit sphere is a sphere of unit radius: the set of points at Euclidean distance 1 from some center point in three-dimensional space. More generally, the unit n {\displaystyle n} -sphere is an n {\displaystyle n} -sphere of unit radius in ( n + 1 ) {\displaystyle (n+1)} - dimensional Euclidean space ; the unit circle is a ...
For example, assuming the Earth is a sphere of radius 6371 km, the surface area of the arctic (north of the Arctic Circle, at latitude 66.56° as of August 2016 [7]) is 2π ⋅ 6371 2 | sin 90° − sin 66.56° | = 21.04 million km 2 (8.12 million sq mi), or 0.5 ⋅ | sin 90° − sin 66.56° | = 4.125% of the total surface area of the Earth.
r is the radius of the sphere, h is the height of the cap, and; sr is the unit, steradian, sr = rad 2. Because the surface area A of a sphere is 4πr 2, the definition implies that a sphere subtends 4π steradians (≈ 12.56637 sr) at its centre, or that a steradian subtends 1/4π ≈ 0.07958 of a sphere.
2.54 cm – 1 inch; 3.08568 cm – 1 attoparsec; 3.4 cm – length of a quail egg [112] 3.5 cm – width of film commonly used in motion pictures and still photography; 3.78 cm – amount of distance the Moon moves away from Earth each year [113] 4.3 cm – minimum diameter of a golf ball [114] 5 cm – usual diameter of a chicken egg
1–2 mm 2: Area of a human fovea [17] 2 mm 2: Area of the head of a pin: 10 −5 30–50 mm 2: Area of a 6–8 mm hole punched in a piece of paper by a hole punch [18] 10 −4: 1 square centimetre (cm 2) 290 mm 2: Area of one side of a U.S. penny [19] [20] 500 mm 2: Area of a typical postage stamp: 10 −3 1,100 mm 2: Area of a human retina ...
S 1: a 1-sphere is a circle of radius r; S 2: a 2-sphere is an ordinary sphere; S 3: a 3-sphere is a sphere in 4-dimensional Euclidean space. Spheres for n > 2 are sometimes called hyperspheres. The n-sphere of unit radius centered at the origin is denoted S n and is often referred to as "the" n-sphere. The ordinary sphere is a ...