Area is a physical quantity expressing the size of a part of a surface. The termSurface area is the summation of the areas of the exposed sides of an object.
Units
Units for measuring surface area include:
square metre = SI derived unit
are = 100 square metres
hectare = 10,000 square metres
square kilometre = 1,000,000 square metres
square megametre = 1012 square metres
square yard = 9 square feet = 0.83612736 square metres
square perch = 30.25 square yards = 25.2928526 square metres
acre = 160 square perches or 43,560 square feet = 4046.8564224 square metres
square mile = 640 acres = 2.5899881103 square kilometres
Useful formulae
}s^2,!|s is the length of one side of the hexagon.|-|Regular octagon|2(1+sqrt)s^2,!|s is the length of one side of the octagon.|-|Any regular polygon|fraca p ,!|a is the apothem, or the radius of an inscribed circle in the polygon, and p is the perimeter of the polygon.|-|Any regular polygon|frac ,!|P is the Perimeter and n is the number of sides.|-|Any regular polygon (using degree measure)|frac ,!|P is the Perimeter and n is the number of sides.|-|Rectangle|l cdot w ,!|l and w are the lengths of the rectangle's sides (length and width).|-|Parallelogram (in general)|b cdot h,!|b and h are the length of the base and the length of the perpendicular height, respectively.|-|Rhombus|fracab|a and b are the lengths of the two diagonals of the rhombus.|-|Triangle|fracb cdot h ,!|b and h are the base and altitude (measured perpendicular to the base), respectively.|-|Triangle|fraccdot a cdot b cdot sinC,!|a and b are any two sides, and C is the angle between them.|-|Circle|pi r^2 ,!, or pi d^2/4 ,!|r is the radius and d the diameter.|-|Ellipse|pi ab ,!|a and b are the semi-major and semi-minor axes, respectively.|-|Trapezoid|frac(a+b)h ,!|a and b are the parallel sides and h the distance (height) between the parallels.|-|Total surface area of a Cylinder|2pi r^2+2pi r h ,!|r and h are the radius and height, respectively.|-|Lateral surface area of a cylinder|2 pi r h ,!|r and h are the radius and height, respectively.|-|Total surface area of a Cone|pi r (l + r) ,!|r and l are the radius and slant height, respectively.|-|Lateral surface area of a cone|pi r l ,!|r and l are the radius and slant height, respectively.|-|Total surface area of a Sphere|4pi r^2,! or pi d^2,!|r and d are the radius and diameter, respectively.|-|Total surface area of an ellipsoid| |See the article.|-|Circular sector|frac r^2 theta ,!|r and theta are the radius and angle (in radians), respectively.|-|Square to circular area conversion|frac A,!|A is the area of the square in square units.|-|Circular to square area conversion|frac Cpi,!|C is the area of the circle in circular units.|}
See also
- Volume
- Orders of magnitude — A list of areas by size.
- Equi-areal mapping
External links
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