List of Formulas for Various Areas

Related article: area area,
measure of the size of a surface region, usually expressed in units that are the square of linear units, e.g., square feet or square meters. In elementary geometry, formulas for the areas of the simple plane figures and the surface areas of simple solids are derived from
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Formulas for Various Areas

Plane Figures	Area¹
triangle	ab/2
parallelogram	ab
rectangle	ab
square	s²
circle	πr²

Solids	Total Surface Area¹
right circular cylinder	2πr(r + a)
right circular cone	πr(r + l)
sphere	4πr²

¹ The abbreviations used are: b = base (length of any side of a plane figure); a = altitude (perpendicular distance from the farthest point of the figure to the extended base); s = side; r = radius (of the base circle in the case of the cylinder or cone); l = slant height (distance from vertex to base of a cone measured on its surface).