## Surface area of a SphereIn this section, we will learn sphere definition, properties, and area of sphere formula along with examples in detail. ## SphereA sphere is a round shape solid object in three-dimensional space. It can be defined as the set of points that are all at the same distance form a given point (center). The perfect example of the sphere is the There is a slight difference between a sphere, and a circle is that a circle is a two-dimensional shape while the sphere is a three-dimensional shape. ## HemisphereIt is the half of the sphere. ## Properties of a Sphere- It is symmetrical.
- It is not a polyhedron shape (a three-dimensional shape with flat polygonal faces, sharp corners).
- The center has equidistant from all the points on the surface.
- Its center does not have a surface.
- Its width and circumference are constant.
- It has no flat surface.
## Surface Area of a SphereThe region covered by the surface of a sphere is called the surface area of a sphere. The surface area of a sphere is the same as the surface area of a cylinder with the same radius and height as the sphere. We can also say that it is four times the area of a circle. Surface Area of a Sphere (A) = 4πr ^{2}The surface area of a sphere in terms of diameter: Surface Area of a Sphere (A) = πd ^{2}Where d is the diameter. The area of a three-dimensional shape can be divided into three categories: **Curved Surface Area:**It is the area of all curved regions of the solid shape.**Lateral Surface Area:**It is the area of all the regions except bases top and bottom.**Total Surface Area:**It is the area of all the sides (top, bottom, and solid).
From the above points, we can conclude that: Total surface area of a sphere = Curved Surface area of a Sphere ## Surface Area of a HemisphereSurface Area of a hemisphere (A) = 2πr ^{2}## Examples
Given, radius (r) = 4.7 cm We know that, Surface Area of a Sphere (A) = 4πr ^{2}Putting the value of r in the above formula we get: A = 4 * 3.14* (4.7) A = 4 * 3.14 * 22.09 A = 277.4504 sq. cm.
Given, radius of globe (r) = 12 cm We know that, Surface Area of a Sphere (A) = 4πr ^{2}Putting the value of r in the above formula we get: A = 4 * 3.14* (12) A = 4 * 3.14 * 144 A = 1808.64 sq. cm.
Given, radius of hemisphere (r) = 6.6 cm. We know that, Surface Area of a hemisphere (A) = 2πr ^{2}Putting the value of r in the above formula, we get: A = 2 * 3.14 * (6.6) A = 2 * 3.14 * 43.56 A = 273.5568 cm
Given, diameter of the sphere (d) = 7 cm. We know that, Surface Area of a Sphere (A) = πd ^{2}Putting the value of d in the above formula, we get: A = 3.14 * (7) A = 3.14 *49 A = 153.86 cm
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